Could you try a dummy if she likes to comfort suck?
1. Can I break the feed/nap cycle?
If you want to, yes. Following EASY (eat activity sleep you time) means feeding upon waking, not going to sleep. This can only work if you have an alternate way to get baby to sleep though
2. How to get a longer nap than 15 minutes?
Don't move her when she falls asleep. Keep conditions the same as when she fell asleep. So if falling asleep on your breast, that means keeping her there. Or maybe get her to go to sleep with dummy in the bouncer and keep that perpetual movement going once she drops off. Or keep the pushchair moving, or the car going if in there.
The key is to not transfer or move baby once asleep. Then having something to suck and some rhythmic movement helps too.
3. Any bedtime strategies to get my evening back? I just want a bath and a tiny break from her!
With all due respect, why are you stressing about bedtime at 4 months old? Put toddler to bed, park yourself in the sofa, let baby clusterfeed and nap on and off until you go to bed.
As time goes on the cluster feeding will lessen and the evening napping will lengthen until baby is spending most ofctge evening napping (in whatever ususl place baby naps downstairs, for me that was the bouncer).
At that point, then move bedtime to early evening, when you know you won't be required for the duration. That's been around 5-6 months for us, usually.
There really is no reason for you to be wasting 2h of your evening faffing with your tiny baby in a darkened room when you could be watching Poldark
4. Does it really matter or should i just go with it?
If matters for your sanity. Mostly your sanity will be better served by just going with it. But if you need some personal space away from baby, that's fine too. You'll need to help baby sleep independantly though - it doesn't 'just happen'.