This is a great thread and I'm glad someone brought it up. First realize that this forum is a little skewed from the real world. While it's great to have a forum to talk to fellow colleagues and prospectives, I noticed that during the match especially certain viewpoints seemed to differ a lot on this forum compared to what I encountered out in the 'real' world.
Anyhow, I am a woman (obvious I hope) and I'm only 4'11''. I actually had many of the same concerns that you do not because I'm worried about what I can do, but more because of others' perceptions of me may have impacted being accepted into gas. I don't know how petite you are, but you'll find that whatever your size, you will adapt and find ways to adjust to get the job done. Basically, if there's a will, there is a way. If you can project that attitude to programs, they shouldn't have a problem with your physical appearance in the match process.
I don't know what the exact breakdown of males:females in this field is, but I can tell you that I've noticed many women in the field who are very happy. I also have seen an increasing trend of female medical students applying to the field as I'm sure many of the program directors will tell you.
As for path vs anesthesia...in regard to patient contact...your patient may be asleep but at least they are alive! I have a couple close friends who are pathologists and they get very little patient contact. In their working situations, they're in a lab the whole day and mostly a consultant to other doctors. Their interactions seem to focus around histo/lab techs and talking to other doctors. I'd definitely say anesthesia has more patient contact. And remember, your patient isn't always asleep such as cases where you use regional blocks or OB when you're doing C-sections under spinal blocks. There's also a lot that happens in that pre-op holding area between patients and anesthesiologists, so don't discount this field as having NO patient contact...there is some.
I'd say the one downside for being a petite female in anesthesia is that people will forever be mistaking me for a CRNA (not that anything is wrong with being one). It's just another time when you can't let ego get in the way, but it does suck that I won't be getting the recognition for all those extra years of hard work just based on appearances alone. Just remember the face of anesthesia is definitely changing!
I hope that helps. Feel free to PM me if you have more specific questions.