Hi Chaly and welcome to Tapas!
So getting right to your questions:
The wall is still an active feature here on Tapas and is for the most part exclusive to the Desktop version of tapas (just make sure you've verified your email and you should be good to go). If you happen to be on mobile though you can still get to it by visiting the tapas website on your phone's browser, just be sure to have it set to desktop site
About the having a story or no story, that one's not too big a biggie. Most likely it would fall into the "Slice of Life" category since your documenting your art journey through comics and slice of life comics in general tend to be pretty free form anyhow
And about this one:
It should be okay (I think) given how you plan to show them and fanart and fancomics do exist on the site. The only hard rule is that fanworks can't be monetized.
I hope that helps and best of luck with that art journey!