Rule Discussion

One thing I was looking up just now is whether someone can Aid with Scouting, but since Scout doesn't incur a skill check, I don't think Aid applies.

Source Core Rulebook pg. 470 4.0
Trigger An ally is about to use an action that requires a skill check or attack roll.
Requirements The ally is willing to accept your aid, and you have prepared to help (see below).
You try to help your ally with a task. To use this reaction, you must first prepare to help, usually by using an action during your turn. You must explain to the GM exactly how you’re trying to help, and they determine whether you can Aid your ally.

When you use your Aid reaction, attempt a skill check or attack roll of a type decided by the GM. The typical DC is 20, but the GM might adjust this DC for particularly hard or easy tasks. The GM can add any relevant traits to your preparatory action or to your Aid reaction depending on the situation, or even allow you to Aid checks other than skill checks and attack rolls.

Critical Success You grant your ally a +2 circumstance bonus to the triggering check. If you’re a master with the check you attempted, the bonus is +3, and if you’re legendary, it’s +4.
Success You grant your ally a +1 circumstance bonus to the triggering check.
Critical Failure Your ally takes a –1 circumstance penalty to the triggering check.

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I also wondered whether two people could Scout for a +2 circumstance bonus, for example. I haven't found anything about it yet, but I think it doesn't stack in that way. I'm just picturing two people being alerted at the same time, not like they'd have extra premonition.

There are three other types of bonus that frequently appear: circumstance bonuses, item bonuses, and status bonuses. If you have different types of bonus that would apply to the same roll, you’ll add them all. But if you have multiple bonuses of the same type, you can use only the highest bonus on a given roll—in other words, they don’t "stack." For instance, if you have both a proficiency bonus and an item bonus, you add both to your d20 result, but if you have two item bonuses that could apply to the same check, you add only the higher of the two.

Circumstance bonuses typically involve the situation you find yourself in when attempting a check. For instance, using Raise a Shield with a buckler grants you a +1 circumstance bonus to AC. Being behind cover grants you a +2 circumstance bonus to AC. If you are both behind cover and Raising a Shield, you gain only the +2 circumstance bonus for cover, since they’re the same type and the bonus from cover is higher.

Item bonuses are granted by some item that you are wearing or using, either mundane or magical. For example, armor gives you an item bonus to AC, while expanded alchemist’s tools grant you an item bonus to Crafting checks when making alchemical items.

Status bonuses typically come from spells, other magical effects, or something applying a helpful, often temporary, condition to you. For instance, the 3rd-level heroism spell grants a +1 status bonus to attack rolls, Perception checks, saving throws, and skill checks. If you were under the effect of heroism and someone cast the bless spell, which also grants a +1 status bonus on attacks, your attack rolls would gain only a +1 status bonus, since both spells grant a +1 status bonus to those rolls, and you only take the highest status bonus.

Penalties work very much like bonuses. You can have circumstance penalties, status penalties, and sometimes even item penalties. Like bonuses of the same type, you take only the worst all of various penalties of a given type. However, you can apply both a bonus and a penalty of the same type on a single roll. For example, if you had a +1 status bonus from a heroism spell but a –2 status penalty from the sickened condition, you’d apply them both to your roll—so heroism still helps even though you’re feeling unwell.

Unlike bonuses, penalties can also be untyped, in which case they won’t be classified as "circumstance," "item," or "status." Unlike other penalties, you always add all your untyped penalties together rather than simply taking the worst one. For instance, when you use attack actions, you incur a multiple attack penalty on each attack you make on your turn after the first attack, and when you attack a target that’s beyond your weapon’s normal range increment, you incur a range penalty on the attack. Because these are both untyped penalties, if you make multiple attacks at a faraway target, you’d apply both the multiple attack penalty and the range penalty to your roll.

Once you’ve identified all your various modifiers, bonuses, and penalties, you move on to the next step.

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You seek out information about your surroundings while traveling at half speed. You use Recall Knowledge as a secret check to discover clues among the various things you can see and engage with as you journey along. You can use any skill that has a Recall Knowledge action while Investigating, but the GM determines whether the skill is relevant to the clues you could find.

Investigate

You Seek meticulously for hidden doors, concealed hazards, and so on. You can usually make an educated guess as to which locations are best to check and move at half speed, but if you want to be thorough and guarantee you checked everything, you need to travel at a Speed of no more than 300 feet per minute, or 150 feet per minute to ensure you check everything before you walk into it. You can always move more slowly while Searching to cover the area more thoroughly, and the Expeditious Search feat increases these maximum Speeds. If you come across a secret door, item, or hazard while Searching, the GM will attempt a free secret check to Seek to see if you notice the hidden object or hazard. In locations with many objects to search, you have to stop and spend significantly longer to search thoroughly.

Search

Your minion acts on your turn in combat, once per turn, when you spend an action to issue it commands. For an animal companion, you Command an Animal; for a minion that's a spell or magic item effect, like a summoned minion, you Sustain a Spell or Sustain an Activation; if not otherwise specified, you issue a verbal command as a single action with the auditory and concentrate traits.

Oh, so I should've taken a -2 penalty to the attacks?

Hero Points
Source Core Rulebook pg. 467 4.0
Your heroic deeds earn you Hero Points, which grant you good fortune or let you recover from the brink of death. Unlike most aspects of your character, which persist over the long term, Hero Points last for only a single session.

The GM is in charge of awarding Hero Points. Usually, each character gets 1 Hero Point at the start of a session and can gain more later by performing heroic deeds—something selfless, daring, or beyond normal expectations. You can have a maximum of 3 Hero Points at a time, and you lose any remaining Hero Points at the end of a session.

You can spend your Hero Points in one of two ways. Neither of these is an action, and you can spend Hero Points even if you aren't able to act. You can spend a Hero Point on behalf of your familiar or animal companion.
Spend 1 Hero Point to reroll a check. You must use the second result. This is a fortune effect (which means you can't use more than 1 Hero Point on a check).
Spend all your Hero Points (minimum 1) to avoid death. You can do this when your dying condition would increase. You lose the dying condition entirely and stabilize with 0 Hit Points. You don't gain the wounded condition or increase its value from losing the dying condition in this way, but if you already had that condition, you don't lose it or decrease its value.