Yea, depends on your style.
In the game I'm running, what I prefer is that the players just say what they're doing, and I ask for a roll when it's needed;
OOC:
Okay, you're bluffing here, so make a Deception check against their Discipline (3 for a Gand), plus a Setback cuz it's buddies are watching.
You can also call for an upgrade, flip a Destiny Chip, etc.
But it doesn't always happens that way. Sometimes the player knows they're gonna need a roll, or WANTS to make a roll to reinforce their rp, or so on and they'll either ask for the Diff, then Edit the post to add the roll after I've responded, or do as Naat said and take a shot at the Average Dif and I adjust it accordingly.
As for Adv/Dis/Tri/Dsp, if your players know the system well enough to know how they want to spend them, they'll Edit the post after the roll results have posted, and say OOC what they want to do with them.