1. Just the space you land on. 2. You are allowed not to move. 3. Well, if you have at least 2 movement points, which you forfeit, then you can say that you apply the risk token to those movement points. I am not sure what to do when you get a penalty token of 2 and only have 1 movement point. It would be quite an unlucky situation though. 4. Yes. Was that a question? 5. Yes. According to the rules, weather applies after all the alpinists move and apply their acclimatisation cards. We usually apply the effect after each climbers turn, but there is a difference, if the weather kills some alpinist - in this case it should stay until all the players move and be removed from the board at the end of the round.
Regarding your "question" 4, I don't think that it costs the three points to pitch a tent. Pitching a tent only costs 1 movement point. Provided that you have enough movement points to move into a space AND have one left over you can pitch a tent with that last one.