Yes. those numbers seem about right.


No.

There is no guarantee.  On average, with that much hash power, you should earn about 0.03299310 BTC per day at the current difficulty of 213,398,925,331.  Assuming an average of 30.4375 days per month, if difficulty doesn't change, then you would expect on average to earn about:

0.03299310 * 30.4375 = 1.00422736 BTC per month.

However, the block reward is expected to be cut in half on July 9 (about 4 days from now), meaning your revenue would also be cut in half to about 0.01649655 per day or 0.50211368 BTC per month.

Additionally, since difficulty changes every 2016 blocks (approximately every 2 weeks), you will almost certainly earn an amount per month that is different than that.  And since difficulty appears to be increasing at a rate of about 3.6% per difficulty change (averaged over the 5 most recent changes), you might expect your revenue to drop by about 3.6% every 2 weeks.  Of course, it could drop a lot faster than that if a lot of new hash power is added to the network, or your revenue could increase if hash power leaves the network.  It's up to you to decide what you believe the future total network hash power (and therefore mining difficulty) will be.


Yes.  By mining in a pool, you pay a small fee to reduce the variability in your earnings.  Without a pool, you would not expect to earn 0.50211368 BTC per month.  Instead you would expect (if difficulty never changed) to earn a single block of 12.5 BTC all at once every 24.89 months on average.  Difficulty is likely to rise before you solve that block, meaning that it will likely take even longer than 24 months (possibly decades) before you get lucky enough to solve a block.


Yes.  The more hashes per second you can try, the better your chance of solving a block, and the more shares you can submit to a pool for payment.