this is more for personal experience, so what I say will not be exactly accurate.
CC is fairly easy to progress in, and as a new player it would make it easier right now.
Would be hard to say if CC is alive and active, there are plenty of players normally on so it ain't so dead looking. Find a group to fit in and it is not so bad.
Pretty soloable just understand battle patterns and you will be fine. Other than it might take a lil long if you lack decent gear on whatever you are doing.
Market is pretty decent assuming you aren't looking on the black market in game, they purposely up the price a bit on there. Though if you look for it on megaphones or discord it will be cheaper (maybe). In terms of costumes, they aren't expensive (assuming you aren't looking for rattus or bai costumes)
This was a question that was asked for a bit when void shut down. Has been assured by Harpy/staff that CC will not shut down or if anything anytime soon.
Not exactly sure what you mean by icons, but dodging usually is just gained through experience in whatever you are doing you usually just time it through muscle memory lol. Though if you need more help through that I think Chiharu has some videos that could help with that? She has a whole post called OnlyClowns with a bunch of videos or even her youtube that you can check out
