- Right now we are running 2-3 Ajax on Home page which cause every seconds it sends request to server.
- Additional SSL certificate need.

We don't know what application(s) you are running, how many simultaneous users you expect, or the volume of requests you will have. It is impossible for us to provide a realistic recommendation for an appropriately-sized server.

That said, you can start with a Linode 1G and test out how your application performs under load. If it's not powerful enough, resizing to a larger VPS is simple.