Leads with FB Ads

I want to generate Leads for insurance niche with FB Ads.

I already have a large list of purchased leads with complete data such as email addresses, name, city, etc. Can I create a custom audience from this email list with FB?
Can this work the way I imagine? do you have any suggestions for me?

p.s: I know that the purchased leads were also generated via fb ads.

Yes, you should be able to import email lists and other informations from CRMs. Next time set up a custom audience for purchases with your pixel, it will be easier. Create several variations of your ads if you didn't find a good combination of ads and placements yet, otherwise you'll be exposing your email list to bad ads that don't convert.

Following...

if you cant get update try to upload to mailchimp, then connect from mailchimp to facebook

Its a list with 5500 Emails. Enough to build a Custom Audience?