My plan is to wait until the value drops and buy some coins. and then sell when the price goes higher on sites like bitstamp.
You and everybody else. So this idea won't work, because by the time the price goes down, everyone else will have bought some too (especially automated trading bots that are faster than you), so the price will have gone up already. Or the price will continue to drop, when you thought it was done, and you'd just lose more money. No one can predict the market (or almost no one, since some people get lucky). If you could do that, you'd have more luck on the stock market. That said...
1. do you use it mainly to make money?
I use it mainly to store up savings that I can take with me when I decide to retire and travel around. That my savings are predictably growing in value is a nice benefit.
2. how do you make money out of it? mining or buy&sell the coins?
Used to mine, but mining isn't really recommended any more, unless you want to set up mining as a professional business instead of a hobby. You could buy&sell and daytrade, but good luck on not losing everything, because everyone else, with way more experience than you, is buying&selling too. Your best bet is just to buy and hold.
3. how often are the big jumps in value? like 50$ differences.
Historically? Maybe once a year. In the future? Who knows. If you're talking about nominal value jumps, like $50, they'll be more frequent in the future, simply because a 5% jump when bitcoin is worth $1,000 is $50. 5% is not a big jump though. If you mean percentage jumps, like 100% or 200%, it's been doing that about once a year.
4. is there any official value? or do i need to go by what sits like bitstamp says? (131$)
Bitcoin is decentralized, and thus doesn't have an "official" anything.
5. how much money do you usually make from buying and selling? im planing on starting with a small amount. like 3 bitcoins.
Since bitcoin is private, most people who make any substantial money wouldn't tell you. But you need money to make more money, and the more money you have the more you can make. Or lose. But if Bitcoin doubles or triples again next year, your 3BTC should be worth double or triple what you paid for them, so.. that's simple I hope.
6. how risky is it? its not like the value drops allot for a long time so there isnt really a risk, especially if im going to mess with 3 coins... (?)
Extremely risky. There is little to no chance of it plummeting to being worthless at this point, simply because there are so many people and businesses invested in it, plus bitcoin the protocol has a TON of uses and benefits (
http://www.whyisntbitcoinworthless.com), but it can still fluctuate unexpectedly, and make you lose 20% or 30% of your holdings within a day or two. That said, if you have enough bitcoins to live just 10% off of, and your holdings fluctuate 30%, you won't really be affected, since you'll still have the other 70%. Also, look into "dollar cost averaging." It's a great investment scheme for things that are generally appreciating in value. Personally, I switched to bitcoins and am using them for all my cash holdings (only other things I hold is USD denominated mutual funds in my IRA/401k), so, to me personally, Bitcoin risk is pretty low.