Also, regarding the pools, where do I have the option of chosing the pool I'd like to join ? I can't find it on my dashboard
Pool fees are paid before the pool pays hashflare, so from the amount you see you only take off the maintenance fees (0.35$ /th) and you get your netto amount.
Right so how can I exactly calculate my expected ROI using a website like https://www.coinwarz.com/calculators/bitcoin-mining-calculator/ ? Is there a way to find out how much the pool fees are before actually buying some hashpower on Hashflare ?
Also, regarding the maintenance fees. Say I buy 7TH/s of Sha-256 for $1050. With the maintenance fees being $0.0035/GH (which in turn is $3.5/TH), am I correct assuming that the only maintenance fees for the whole duration of the contract (1year) will be 3.5*7 = $24.5.
Here you have a list with pool comparisions and fees. https://en.bitcoin.it/wiki/Comparison_of_mining_pools
But i'm not so sure if it's up to date. it would be best if you check on the pool's sites cause sometimes they change fees.
the fee is actually 0.35$ / terahash / day. so for 7 th/s you would pay 2.45$ in maintenance fees per day.