You should defintely continue uploading your stuff, and yes you may include your older performances too, you can make a post about those, it's yours, no worries.
(@dsound and @dtube tho is still quite laggy at times..)

Yes you can sell your stuff on dsound, the whole thing is very simple:
After uploading you can set a "buy" button instead of "download" then after every purchase you'll be paid on the uploder account in SBDs.
(Although I've never tried to sell my stuff there,you can give it a go)

Every kind of original content is welcomed, you could totally share things about yourselves, what's going on, what are your plans etc. or whatever idea you come up with. For example when you go on a trip like now to LA, you can make a post about that, take a lot of nice pictures and tell it as a story in #travel.
These kind of materials are gold and maybe even @curie or @ocd will bat an eye on you.

Keep competing in openmic and look for other steemit contests, music curation programs, use resteem services like @resteemable, @resteembot, @hottopic.
Right now I can't really suggest any more steemains, curators or services, as I was off for the past year, so I have to cath up. Basically I'm doing the same thing that you should do after you came back from LA. Talk to people, surf steemit posts, promote your stuff.
If you do these things consequently your blog will explode sooner or later.

I wish you the best of luck and a ton of success,
I'm looking forward to hear more from you.

STEEM ON!