There is, just because a majority of the Multiplayer servers run it really makes it a bit more popular.
I don’t think you do. It should be ok on the version you have. Just use the ‘Saved Games/DCS’ folder rather than ‘Saved Games\DCS.openbeta’ and you’re good.
No, or rather you can have two installs if you want - the settings files are different, so it’s really a question of disk/SSD space.
If you do want to try the DCS Beta (you don’t need to for this T-45) then @SkateZilla’s tool is very popular:
No, the free one that comes with DCS works ok too. The SupperCarrier just has the fancy people running around.