Welcome!
Do a google search for InTank Media Basket. That should get you on the right path. I used one of their media baskets for my first tank which was also a 29gal biocube. Great beginners tank. I'll probably get another someday for upstairs. The media basket makes it much easier to provide good filtration for your tank. I typically ran filter floss on top, chemipure or purigen in the middle basket, and matrix on the bottom. You'll understand once you see one.
I agree that a little more rock is probably warranted but you do want to leave swimming space for fish.
One test kit you don't have is Nitrate. I generally use a Seachem alert badge for ammonia and then test kits for nitrite and nitrate. In your case, if you haven't already, go ahead and test for ammonia and nitrate. Post the results here. If you used live rock, it's possible you won't really have a cycle at all to speak of. Based off the pictures it looks like you are already going through the new tank stages.
Feel free to clean the glass any time. No reason not to. If your ammonia and nitrite come back at 0 you can add 2.5ppm of pure ammonia, not scented or anything fancy, just pure, plain ammonia, and test ammonia and nitrite again. If it's still 0, then your cycle is done and you can add a clean up crew of snails. Since you seem to have an in with a LFS you can likely get them there.
You've come to a great place for research and advice. This forum has a great search feature in the upper right but you can always feel free to post your questions if you can't find what you're looking for.