1.Well to start mining you'd first need to know which cryptocurrency you want to mine, but before you can do that you'll have to know which algorithm is the most effective with your hardware
Because this might sound a little complicated I recommend you download
NiceHash's miner, it's a miner that chooses the best algorithm for you and pays you in BTC (I assume you've already set up a BTC wallet). You can monitor the progress on NiceHash's website and see when and how much you'll get paid.
2. Cloud mining is rather frowned upon in this community mostly because 9/10 cloud mining providers have turned out to be a scam, and even if your provides isn't a scammer it's really hard to turn a profit. So I wouldn't recommend you invest in it.
3. I've never used Minergate myself so I can't comment on it
4. Not sure what you mean with that, I'm going to guess you mean "damaging". If so just make sure your GPU and CPU are sufficiently cooled and make sure they're not overclocked, but I think you're setup has that already.
Good luck and happy mining