Individual Email Addresses for each website?

It depends on (a) your users and (b) your capacity to effectively use all of those accounts.

As for (a), if you have two different sites, one targeting gay Republicans and the other targeting homophobic Democrats (obviously I'm just making this up), I'm guessing that keeping everything separate is the way to go. On the other hand if you have a site on 1968 Volkswagen Beetles and another targeting people with 1969 Volkswagen Beetles, you'd probably be pretty safe combining them. Yes, these are extreme examples, but just use your common sense to figure out if the content from the various sites makes sense to share across a single FB page. That said, if it makes sense to have different websites, it probably means that it makes sense to have different FB pages.

As for (b) the question is whether or not you have the ability to manage and add quality content to all these platforms. Multiple email addresses are easy -- just have them all forward to the same box and make sure you're replying with the correct "from" address. Facebook and other social media gets more tricky. In my mind, if you're not willing to invest quality time in quality content, social media isn't really worth doing. I'd rather have one active and engaged Facebook page than 100 inactive and unengaged pages.

The emails adresse does not matter at all.

Thank you for those answers trying to get a hang of this