Battle of the sexes: Retic edition!

[AbsoluteApril]

SIZE: If i feed a female the way breeders feed their males, would she stay small(er)?

It varies and depends, my gut would be to answer this with a no as in she wouldn't stay the size of a male. From what I've seen, females are heavier/girthier in general overall even at the same length as a male.

ATTITUDE: I've heard/seen a lot of talk about males having the potential for less predictable and potentially more dangerous behavior, also the infamous "combat teeth" (is this really a thing?).

I don't know what "combat teeth" means? I will say that yes, males get antsy and can be bad at breeding season, at least we've seen it here but there are females and males, so breeding season is always a 'thing'. They have big teeth and can do serious damage, always treat with respect and be aware of the snake's attitude.

CHOOSING: Do nasty baby retics turn into nasty adults? Do sweet ones stay sweet?

You have a burm, so in general you probably already understand how burms can be hissy pissy babies but will grow out of it in time.
Generally, retics are calm or going to be calm over time*. We've yet to see a nasty baby here (knock on wood), some might be a little nippy (hungry) but haven't had any issues with them calming down as they grow. I'd say that yes, sweet babies generally stay sweet.
*this does not take into consideration breeding season issues - those are seperate issues.

All snakes are different so it's tough to give black and white answers for these questions, please just keep that in mind.
Hope that helps