Hi, congratulations on your new bundle!
Yes, at 4 weeks it should be a 3h EASY, but many babies don't get to that. Many still need to feed at 2-2.5h (also depends if she is BF or FF), so at this early age it's still more following her cues.
DF is at 22-23 but you should still expect more NF, it's just to give YOU a better stretch at the beginning of the night. I personally had to burp after the DF and any other NF because DS would wake up at 4-5AM which very bad wind if I didn't. I would offer a normal bottle for the DF and it's ok if she doesn't finish it.
Nappies you don't need to change unless she is soaked through or she pooped.
Maybe this will also help:
Starting EASY - all you need to know and more!Good luck and we are here if you have any more questions