New seller questions?

So I have been looking into selling on amazon, so far I believe its £39.99 per month plus £0.99 per item sold.

I have been looking into ali express bulk orders, Is there a way of seeing how much import fees will be?

And is it true you can ship your ali express order directly to amazon warehouse?

How do payments work? Are you paid every time you sell an item? Or can you build up payments and withdraw them?

And how do you go about finding the right product that will sell?

Thanks in advance!