What percentage will we receive yearly if we hold BMF tokens in our account and how many will we need in order to Stake?
The yearly return you can expect will depend on the price that BTC will reach.
There is a BFM return calculator on the website to estimate your payout. You can input the amount of BMF you want to purchase and your BTC price hypothesis to find out how much you will be making by using their Mining Operations and Services
https://www.bitminerfactoryico.io/en/