Imperious
Without the sun of my life
Not necessarily, or even likely really. As a Grail Knight he's more likely to be sent on some mission by the Lady/King or go do something she'd approve of. Unless the Lady feels that his lands need specifically him he's unlikely to be sent to be on permanent retainer next to them. It's not like he has a fief to lord over either anymore. He relinquished it when he went on the Quest.Would also finally allow Roland to return home to his family and give us direct access to the country in general.
Duty doesn't end after you finish the quest. If anything it merely starts.
He is likely to be sent back to Bretonnia though yes.