If you have something like spellguard bracers, or focused mind trait, can you use those concentration increasing abilities on scrolls? How about the ability to roll twice with the spellguard bracers?
I don't see any reason why you would not be able to. The concentration is a factor of your character not the scroll.
Interesting. so the feats increase the concentration of items like scrolls.
No that is not at all what I mean. If your character has to make a concentration check while using a scroll then the items would help him/her.
Concentration is NOT built into a scroll and those items or ablities effects cannot be put into a scroll either.
Another way to state it is: Scrolls don't concentrate, your caster does.
Scrolls are like casting a spell - just don't use a spellslot/prepared spell but the scroll instead. So if you do it denfensively you get the bonus...
Yes - unless your class says otherwise (there's a few ways to use your owm).