Hugs, it's so much harder second time around in some ways isn't it!
First, yes....ditch the swaddle. If you can pop her into a sleep sack/sleeping bag so she can move around. Give her a lovey or something to learn to snuggle into to satisfy her fidgeting (a muslin cloth, or little blankie, soft toy etc)
4 mths is a huge sleep regression anyway and your probably in it already so you may as well start on ST etc.
What does her day look like EAS? - or at least her A times between naps.
So in answer to your Qs...
1) feed as close to 3 hrs as you can, or when she shows hungry signs. Your day will be a bit EASAES if she's short napping but that's ok
2) yes ditch the swaddle. I personally would do anything I needed to for the next few days to get my kids to sleep without it, then move to independent sleeping in the cot with shh/pat, gradual weaning or PU/PD. You can use a version of sh/pat your lo likes (my boys liked their bottoms patted and white noise). She's a little young for PU/pd and it can OS.
3) I think I popped my toddler in front of the telly a bit, and recruited family help when St
I did 1 nap on the go ie wrap and another when my toddler napped. Or, I did 4 shorter naps and just want with the flow. We did a lot of apop in the early days because you just have to find what works, and in our house it was the easiest all round till T was closer to 8 mths.
Does any of that help at all?