In about 2 or 3 years, sure. Rusty's still the President for another 2 years (he's a 3rd year right now), so unless something dramatic happens where both Rusty and Tommy were to be ousted from the DIKs or had to step down from their positions, the MC won't be becoming President for quite some time.
Not necessarily. That "feeling" (I won't say what feeling) has typically been associated with seeing a LI with another man, but if the LI you like is with another woman and is taken by her, is it not the same? Or if you like 2 female LIs and they're taken by each other?
Granted, flashbacks are not "that", but the M&J flashback can create that feeling just as a possible flashback of Bella and James can.