Hey guys :D

I'm new here and a new runner as well. I'm 19 YO and have been a trained dancer (ballet, modern, etc) for many years. The last two years however, I've fallen out of dance training to pursue other interests. I have remained fit, but have decided that I wanted to become a dedicated runner to keep in shape, be active. I've quickly, in just three weeks, noticed myself improving. My breathing has gotten much better, feel healthier, etc. I've begun a training regiment to run a half-marathon, have great running shoes, and follow a strict vegetarian diet (for the past 5 years). I've researched extensively, but I'd like to ask a few questions to real people though to solidify some information...

-- Is a half-marathon in 10 weeks too soon? (Breathing is good, weigh in at about 120 at 5'3'', decent dieting habits-- yet perhaps these things won't matter)
-- I have ankles that roll in, know any corrective measures? Will pronated ankles hurt my running?
-- How long should I be stretching before and after?
-- Is it necessary to carry water on long runs?


These questions may seem naive, but I indeed am unwise to the ways of running beyond the basics. So here I am! Thanks for the help!