I recommend another vet. No credible vet would make those suggestions- I cannot imagine i! I can only tell you that if it were me - and I HAVE treated many a sick kitten, waiting and hoping and praying they'd make it though the night (sometimes with a vet a100 miles away) - that what they vet suggsted makes no sense. That wound needs to be seen asap - no time to wait. Even if I had a kitten and a vet 100 miles away, I'd be in my car or someone else's and on my way to the first other vet or open emergency pet ER!
As for feeding her, she needs liquids so water or KMR(which you can buy at any pet food store, pharmacy or grocer) should be forced into to her somehow and by that I mean,, easily. Get an eye dropper or a syringe (a pharmacist at a drug store will give you one of you show him/her why- show him the kitten if you have to but my pharmacist once sent a bunch of them in a rush for kittens when I called them in a panic) (I had 4 mewing kittens without a mother and closed eyes who were maybe 2 days old). Push the water/KMR in her mouth bit not too hard - make sure she swallow some by gently rubbing her throat as it goes down. (Like when you give a cat a pill). Kittens NEED fluids!!
I do not get why this vet did not suggest you bring her over immediately. My vet would have asked me to bring her or other kittens there immediately given the situation you describe. So call another vet and find one who will help the kit!!!