[2020] Start with RBS Siege

Hi guys!

Just wondering: is this a suitable game for new players like me, who intend to start five years after original release? Is there any system which puts players in a game based on rank/level or something?

And I see a lot of different game versions. If i just buy the standard edition, can I unlock all the operators which are added by other game versions, just by playing?

Thanks in advance!