Hi,
If you have 2 separate business, then you will need 2 quickfile accounts with 2 different email addresses. Alternatively, you could use affinity to be able to see both business under one login.
You can certainly connect the right stripe account to the right quickfile account.
I am not completely sure with your one bank account for both quickfile accounts, but theoretical it should be possible. But to be honest to keep things simple I would open a second bank account so you have 1 for each business.
If you have two trades under one business, then you only need one quickfile account, and you can use 2 different trading styles. The downside, as far as I know you can only connect 1 stripe account to a quickfile account.