So if I rent on WestHash I should just choose to not limit the hashing power because it doesn't make a difference in the chance i solve a block. due to the same amount of hashes?
The 'number' of hashes determines the chance of finding a block.
If you run 10TH/s for 1 hour - that = 10TH x 3600 seconds or a total of 36PH
If you run 360TH/s for 10 seconds - that = 360TH x 10 seconds or a total of 3.6PH
The expected average Diff to find a block is currently 46684376316.86029053
1 Diff = 2^32 Hashes or ~4.3GH
So currently the expected average number of Hashes to find a block is ~2.0x10^20H or ~201EH = ~201000PH
Note above where I have said "GH" or "TH" or "PH" that is a total number of Hashes
Where as "TH/s" is a number of Hashes per second