Demagor, regarding your questions about 5 foot steps and weapon swapping:
Rules as written, is no similar mechanic to 3.5's five foot step for all characters in 5e. Some classes have built-in abilities to do something like this, however. For example, rogues have the "Cunning Action" class ability that allows them to take the Disengage action, but it uses up their bonus action. Monks eventually can spend ki points to do this. Rangers can select the Escape the Hoard feature at level 7 as a defensive tactic, which makes all opportunity attacks against be made with Disadvantage.
I think the five foot step was deliberately omitted from 5e. If you can take a five foot step, it is almost always the right thing to do for an archer in that situation. Without the five foot step, you have a more tense decision to make: Do you fire at point blank range but with disadvantage? Do you pull back and risk the opportunity attack? Or do you switch to a melee weapon that is probably not your specialty? Maybe you are incentivized to design your character to excel at one of these backup options through class features, feats, multiclassing, magic items, etc.
As far as swapping weapons, I usually house rules it as okay. Rules as written, you'd have to drop your bow (costs no action) and then draw your melee weapon with a free action. But, on your next turn you could just drop your melee weapon and pick up your bow as a free action, so unless you are moving around a lot, there is a goofy-looking weapon swap within the rules. For me that interferes with the fiction of competent martial heroes to drop weapons and pick them up again, whereas it sounds pretty cool to switch weapons with a cool flourish. That's my reasoning anyway.