Plans and how it all works

I am used to standard web hosting - I want to start to try to use this kind of hosting for better speed. Some simple questions please if you know that answer I would be grateful. a) If I have a droplet - how many websites can I run? My sites typically have 40 -100 visitors per day. I was looking at the 10 dollars per month plan. b) As a shared host looks after a lot of stuff (If the server goes down etc they have 99+% uptime) does anything like this happen, like with AWS I am assuming I am fully on my own. c) Can I use letsencrypt with you to get free SSL - this works on my current host well. d) Will your droplet serve resources from closest physical locations? I understand that aws has route93 that allows edge servers to be configured to serve up assets closer to the request browser.

Thanks.