5.f. Well, really, I designed the relationship around a character who’s attracted to certain things and turned off by others. The game presumes an initial strong physical attraction just to get things rolling, but you can definitely cancel that out by behaving in ways Breden finds unappealing. As for the four loves, if you were speaking koine with Breden you’d doubtless be using eros to describe his/her love. Agape’s a little too lofty and disinterested, philia not impassioned enough, storge too familial.
6.c. There’s no law forbidding marriage between free provincials; but for an aristo to marry a merchant would in effect end their recognition as noble by their peers. They’d be permanently stepping down a huge notch in social status and privilege. As a result, Houses that lose their land generally end up forming a subcaste that can/will only marry other similar unfortunates. They usually can’t find an opportunity to marry up, but marrying down would be to forever remove that alluring possibility.
Your family, if you’re an aristo, is not quite reduced to that level; and your father has doubtless been doing everything he can to find a way to marry you up before settling for an even less fortunate family and continuing (likely cementing) your House’s downward spiral.
The Canon prescribes that the eldest child inherits any lands and houses belonging to the family. All other property may be freely apportioned by the matriarch or patriarch in a will witnessed before an Ecclesiast. At marriage, spouses become co-owners of each others’ property, and one spouse may complain legally to the Ecclesiast or aristarch if the other disposes of that property without mutual consent. There’s a strong incentive for provincial families not to (officially) squabble too much over property, as wherever ownership of property is deemed legally unclear it may be confiscated by the authorities pending resolution… which then rarely comes.
Yes, there will be opportunities to affect Anarchy in Ch 3 of the game. You could murder the Archon’s cousin, for example… that can’t help but affect people’s perceptions of how much the authorities are in control. You’ll have some choice of how you respond to Hector coming after you. And you could start a religion. 
Now back to writing all that stuff.