9 pending cards

Well, you don't have to make any hard decisions for another 10 days.  The first thing you need to do is set a 3* Bonus Hero.  I would suggest Iron Man from the 3 you have rostered and then switch it to someone else once you have 4 in one color.

If you do have to make some hard roster choices, selling 1* heroes except 1 would be my first suggestion.  You only need to keep 1 to be able to do the DDQ node.  I would suggest holding onto Iron Man.  With the changes they just made to xp gain, you can use the extra covers you end up pulling on him to get some xp, not like you will severely **** your ability to do the DDQ node with all the different cover combinations on him.  

None of the 3*s that you have waiting to be rostered or sold are top tier, so I would prioritize the 2* heroes over them to roster.  Doctor Strange and perhaps Gambit are the only ones along with Iron Man that I would consider rostering over one of the 2*s.

Aside from that, other caveats to keep in mind, don't spend your HP on anything other roster slots, don't spend any Legendary Tokens or Command Points until you have at least half the 3*s in the game champed and are ready to transition into the 4* tier.

Welcome to the game and enjoy!

An easier way than screenshots to keep track of your roster is to use https://mpq.gamependium.com