1. The anonymous factor is what attracts quite a few people. They do not want big brother looking over their shoulder in terms of what is going on with their money. At this point most people still have to go back and forth between BTC and USD, but in the future most true believers hope that wouldn't be the case. You would be able to pay for items/services directly and not need a USD middle man. Also the fact that there is no real controller/regulator attracts others, while it also might create drawbacks, it is still quite different versus anything else out there.
2. The comparison between folding and mining is probably one of the closest that can be made. The resources are purely used on the computational aspect. Mining is needed to prevent all of the coins being released at the same time. By 2140, 21 million bitcoins will be available. Depending on the mining and hashing speeds, the difficulty and rewards change. For example, the purpose built ASIC mining units that are suppose to come on the market in mass this year will allow for greater computing power in terms of mining. Due to this the difficulty to get rewards through mining will rise. This will keep the mining outlook the same.
3. As far as anyone knows, bitcoins are currently unhackable. Wallets/exchanges etc have been targeted due to their security issues, but never actual bitcoins. I read articles about Black Hat hackers trying their luck as well as others with no success. Someone did an article about Satoshi Nakamoto, the create of bitcoins, and they were quite surprised with his coding work. They stated it is unlikely that he was a programmer by trade due to the look of the code. With that said, they mentioned that the code was surprising clean and very well made. It seemed the he was a self taught coder/economist because he took so many considerations into the project and tried to make sure most if not all issues are addressed before hand.
4. All of the volatility issues are due to the dependency on the main bitcoin exchange, Mt.Gox. For them volatility is business since it pushes transaction numbers up. When trading stagnates, a DDOS attack on the exchange creates 1000s of frantic trades putting transaction fees in their pockets. Until more exchanges take the load off Mt.Gox and security issues are improved all around, it will probably continue. Mt.Gox supposedly has a new trading engine that is going to be released in late June along with new, more dependable hardware. In addition, the DDOS attacks are having less success now because all of the people with little knowledge have been removed. Most people at this point see an attack coming and just forget about it without going into panic buy/sell mode. This causes the price to fluctuate only 10-20 USD vs. 200 like it did earlier in the month.
5. Mining increasing is hard to explain. Like I mentioned before, more computing power equals more difficulty. For example, a year or 2 ago simpler and less powerful hardware could have been used to get a certain amount of bitcoins vs. now. I believe the rewards for a solved blocks (look at it as solving a math equation, right answer = reward) are still 50 BTC, but due to the in increased difficulty in solving the blocks, more hashing power is needed. I think it is safe to look at it this way, more people > more overall hashing power > difficulty increases. When ASIC mining units are going to be released, they will increase the difficulty so much due to their greater hashing power that GPU mining will be close to obsolete. You won't be able to break even with your power bills.
The things to know is that there will be a max 21 million bitcoins total in existence. In addition this number will probably be much lower due to lost bitcoins, once they are gone (deleted wallets/HDD crashes/etc) they are not recoverable. At this point bitcoins can be broken down to the 8th decimal place if need be.
I am not an expert on bitcoins and the above is just from things I read. If something is wrong, correct it.