in middle of game, have question...the rogue trader's ability to add 10% to any skill...can he declare this after the roll? or does it have to be before

Generally, modifiers to a roll must be applied before the roll is made. Since no exception is specified here, I'd say it should follow th general rule.

I agree, bonus should be applied before the roll.

I also have a somewhat related question, the rule states he can give this bonus "per round" does that mean it is only available when the game is following "Structured time", such as combat? Or can he pretty much foist off +10%s whenever he wants?

I am going to presume its the "Structured time" thing. Though as long as they are keeping the bonus for actions of critical importance and not trying to give a +10% to every single action his allies make out of combat, I could see letting it slide.

I also have a somewhat related question, the rule states he can give this bonus "per round" does that mean it is only available when the game is following "Structured time", such as combat? Or can he pretty much foist off +10%s whenever he wants?

An astropath's divination powers take up a full round action - so he can't use them while he's not in combat?

I am going to presume its the "Structured time" thing. Though as long as they are keeping the bonus for actions of critical importance and not trying to give a +10% to every single action his allies make out of combat, I could see letting it slide.

Giving +10% on every single action his allies make is pretty much what the RT class is about. Or would you say the Void Master shouldn't use his Master of Small Craft ability on every single pilot roll when using small crafts?

"Bluff, Bluff, Bluff the stupid Ogryn..."

Some things it does seem a bit silly for, but I guess those are the rules. Maybe it's just a stern glare and a mumble about the need for new servitors, and suddenly you're REALLY inspired.