Is there a way to use http and https with Xenforo

I'm going to preface this post by saying I am still learning about what SSL entails, and the differences between http and https, so I will probably misspeak at some point.

My website host, WebHostingHub, charges $100/year for a dedicated SSL certificate. I may end up going that route when I have the money to do so, but in the meantime, I had a couple questions:

1. Is it better to force https for all users, or allow users the option to use http or https?

2. If I set up my site such that when someone types in "" it goes to, will people without https support (I imagine older IE versions or something) be able to view my site?

3. My host offers a shared SSL, but the url is different from Is it possible to host the same site (users posting through or, such that all users will be able to post and view the same content?

EDIT: This all refers to using a Xenforo forum, but especially with regards to #3, will Xenforo allow me to direct to the same content through http and https?