Like you, I came back after a year hiatus and a lot has changed, some for the better, some for the worse.
While I cannot give you the exact answers to the questions you are asking, here is a link to the top builds: https://treeofsavior.com/page/class/ranking.php
Generally, the classes maintained their roles from the previous iteration of the Class Tree system so tanking would fall to the peltasta or the rodelero, etc.
As for which combos deal the most physical/magical damage, I cannot give a direct answer again. Look for the classes that allocates the most stat points to the desired stat. This is generally reflected well in the top builds in the link I provided above since most players would go for most damage.
I hope this helps a bit. The new Rank System sort of sucks but at the same time, it allows for experimentation. In your return package, you should have class reset coupons and skill reset pots, in which case just experiment with what you find to be most enjoyable. (still a crap system for the game’s longevity though)