Hunting elk is very similar to hunting deer. Elk are massive in size when compared to deer. Be sure to keep a keen eye out as elk are very elusive and blend in with their surrounds very well for sure a large animal. Have fun and good luck!
A good old fashion military mummy bag would do. Both of my brothers and I were all in the boy scouts when we were kids and we all used mummy bags and never got cold.
I've always been a rifle hunter. I recently picked up a Parker Hunter Mag w/ a 60lb draw. I've been practicing with it every chance I have been able to get. I'm excited about trying out archery hunting. Not to mention the tags are over the counter here in AZ. No wait to see if you get drawn.
I wouldn't be doing any off-roading with a 3 wheeler. Too unstable. A quad is safer by far. But for general puttin around, either would work just fine. 3 wheelers are still legal in Cali, look at Trader Online Magazine New and Used Classifieds For Sale - TraderOnline.com for some for sale.
I would have to agree with Dinosaur. A .223 (5.56mm), a .243, or even a 30-06 would be best suited for a woman of your size. Anything bigger than that will be overkill for your shoulder. My wife is roughly the same size and she won't even touch the two rifles I shoot. A Savage .270 and a...