+1 to TabisFish. If you plan on any sand dwelling/burrowing animals you will want the rocks on the glass. If it's just a shallow bed you can twist the bottom rocks down into the sand and that should prevent a rock slide.
If your rock is being shipped you should have some die off and that should be enough to kick start your cycle. You can add a small uncooked shrimp if you want to move things along but likely not needed.
Phosphates are one of those things that really tends to build up in tanks if left unchecked. Yes your WC's will help to remove some but any that bind to the rocks, etc, will not be removed and it doesn't take much to start algae growth. You can certainly try without and if your water source is good, you feed the right foods (rinse frozen foods) and appropraite amounts and you stay on your water changes, you might be fine. Again, something like Chemipure Elite is a good all in one for smaller tanks. Chances are you will get the typical alage blooms after your tank is started so don't feel like you have to run out and buy a bunch of stuff to fix that. Just stay on WC's and get a good CUC for the intial blooms. The phosphate remover would help keep that down though.
The other thing I would do with each water change is use a small pump/PH or turkey baster to blow the crud out of the crevices in your rock and the siphon the water out.