Questions from a novice

Novice swimmer here, 40 y.o. male. Never had any formal instruction, then started up with my local masters club about 9 mos. ago after an injury forced me to cut back on jogging. Hoping some of you old pros can help me out with answers to some basic questions: 1. Are there any muscles that swimming DOESN'T develop, and that I should work separately in order to have a "balanced" physique? For example, if you do quad exercises, you also want to work the hamstrings. What are the "equal and opposite" exercises I should do to balance out the swimming muscles? We always do some IM sets so I'm getting in at least some work in all 4 strokes. I also continue to run, about 15 mi./wk., altho I don't know why--most of the time I'm thinking I'd rather be swimming. 2. I live in CA and swim 3x a week in an outdoor pool at lunchtime so I'm getting lots of sun exposure. BESIDES sunscreen, is there anything I can wear in the water to protect at least my torso? I tried a rash guard once but it was too "draggy". Maybe I just need a really tight one. 3. My *** stroke kicking is especially bad. I think it's because I have inflexible ankles. In the "fully loaded" position, I can't seem to get my ankles cocked enough nor my feet turned out enough. Is there a stretching exercise to improve ankle flexibility? 4. How do I know when I'm ready for (i.e. able to finish) an open water swim of say 1 mile in a lake? Yardage in a pool can't be the same . . . you rest between sets, you push off the wall, there are no waves, you don't have to look up to navigate, it's significantly warmer, etc. Is there a rule of thumb such as, if I can swim 2000 yds continuously in a SCY pool I should be able to swim a mile in a lake? I don't mind finishing last, I just don't want to have to be pulled out of the water! 5. What and when do you eat and drink before an open water swim? Thanks in advance!