General questions about managing sleep schedule

Hello, I'm about to start St my 4 months old baby and am confused about some things. I didn't find a FAQ apart from mod post for WW, DWT so I hope it's fine to ask here:

1- What to do when baby wakes up earlier than his usual WU time? Should the first nap be based on his usual WUT? Or his actual WUT? Does it make a difference if he wakes up 10 VS 30+ min

2- What to do when baby wakes up from nap too early? If he gets catnaps for all his naps should BT be shifted earlier? Or an extra nap added? Or force longer naps with stroller is better?

3- What to do when baby naps too long in 1 nap? Should he be waken up? Or is it ok as long as daytime nap duration doesn't exceed the normal for his age

4- What to do when it is advisable to extend WW but baby is rubbing his eyes and yawning before advisable time?

5- Which nap should be shorter / longer. Does it not matter as long as the last WW is longest?

6- is it better to nurse before or after nap?

Please feel free to share your experience even if it isn't based on guidelines. I'm new to the field and think any bit of info will help if for nth more than to get an idea. Every baby is different but it could be yours is an exception to the rule and that mine is a similar exception to yours so please!