Hello guys. I currently installed a Joomla website in Vesta CP in your Droplet but I encounter a few issues.

Firstly, I have a component, Payplans, which function well in my old(shared) server but when I move it to your server I have problem because it don’t let me to save changes in Administrator area. The same issue is also for general configurations of Joomla. I understand that this is a permissions problem, but the default permissions of Joomla, not worked here. To make these files can be saved I have to give 777 permissions and obviously this is not good for me. Do you know what maybe the problem and the difference between my previous server and your one?

Secondly, I noticed that if I login in administrator area, it never log me out automatically. This may happens because SESSION or some other variables are not set? How can I fix this?

Finally, I am trying to make a working mail with Vesta CP. WHat MX Records I have to point out to make a working mail? Are below correct?
mail.domain.com 5
mail.domain.com 10