hiya!
1. Starvation is caused by not having food available when you camp at night. Think of it like "going to sleep hungry". The only time you can eat in the game is when you camp. So if you had food, your starvation counter would reset to zero.
2. Yes! The taser is a general weapon and can be used in combat. Check out pg. 52 for info on items you find. The taser is solar powered and can only be used once a day. Great for getting out of a pickle. It will also stun the enemy, a combat effect you can find on pg.09.
Good luck! Happy to answer any other questions you think of!