>>716381117
1. You're playing Hard mode, so yes, definitely you can get all the kids. Just make sure you don't slack on building S supports once you've decided on them.
2. Galeforce is kinda overrated. Get it on units that require minimal effort for it, but otherwise don't bother.
3. Dunno.
4. Mechanically the two best kids are obviously Lucina and Morgan. Other than them, Nah can be a really good juggernaut, and basically whomever Donnel ends up fathering will be good by grace of Aptitude inheritance. Pic related.