Goggles and a comfortable suit are the only 2 things I definately suggest.
TYR Racetechs are my fave, and are less than 10 bucks. I have very very close set eyes, and these are great. Nice large gasket. The only time they leak is when I make odd faces during my flip turns, which cause my face to squinch up. Doesn't happen as much now that I've gotten better at them though

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A silicone (NOT latex) cap is required only if you have long hair that gets in your mouth when you breathe, or you don't want to ruin your hair with repeated chlorine exposure. I don't use special chlorine removing shampoo, just a cap and good deep conditioner, and my hair is fine. --I don't color it though. YMMV
If your knee is an issue, and you really don't want to put ANY strain on it, a
pull bouy is a great tool for isolating your upper body, and focusing on your stroke. There are many styles, the link is just to the one I have. You just put it in between your thighs, and it holds your back end up so you don't have to kick at all.
Good luck and most importantly,
have fun !!!