What kind of hashing power do i need to mine solo and what is the pros/cons by doing that?
You would need a few gigahashes but compared to p2pool solo mining has no pros and one con: higher variance
I think the only decision you have to make is wheather you should use a traditional pool or p2pool.
The biggest advantage centralized pools have is the low variance. For example you have the hashing power to generate 1BTC per day which means 30BTC per month. A tradiotional pool will pay you very close to 1BTC every day so you have a steady payout.
At p2pool on some days you get nothing on someday 1.5BTC and one other days 2BTC but if you mine for one month you will get 31BTC.
Another advantage of p2pool is that it's decentralized which is probably healthier for the bitcoin network but also it can't be shut down, hacked and theres no operator who could steal bitcoins from you if he wanted to. There's no single point of failure.
I think that your not going to run your rig for only a few days so the variance shouldn't be a problem. I mean why would you care if you get nothing today but 2BTC instead of 1BTC tomorrow when your running your rig for several months anyways. That's why I'd suggest to go with p2pool but it's your decision.