Looks like more than I would want personally, but it is really a matter of what you like the looks of. You limitations to consider are flow, water volume, space for coral to grow, cleaning the glass around the rocks, detritus and probably some others that I am forgetting. Oh..... money! haha!
If you like the way your tank looks that is all that matters, but it is important to remember that you def. don't NEED all of that rock and that the LR is not going to do a ton for your biological filtration in the long run, so only scape your tank with as much rock as looks good to you.
Not necessarily. There are better options for biological filtration. Even your sandbed (if you are using one) will provide more surface area for bacteria to grow.
Having more water volume and flow around the rock will help to keep detritus in check. Growing more coral taking up that space will take up more excess nutrient as well and look better too.
I also noticed your return is rather deep in the back there. May want to raised that up or make sure that your sump can handle the volume in the event of a pump failure or power outage. If you are using a siphon break or a check valve instead make sure to keep it clean!
Nothing wrong with moving to elsewhere in the system. Just make sure that wherever it goes that there is plenty of water flow around it and that you keep it clean and free of detritus buildup.
I kinda like it. But I'd add some real serious powerheads to create a bunch of turbulence, wave like, to flush the rock free of detritus. Kinda reminds me of those manmade jetties you see around some beaches and harbors. Lots of crabs, mussels, and quick aggressive fish would be interesting.
Yup. Just keep that break clean. Stuff loves to get lodged in there! Also, keep that light turned down on the red, green, white, whatever it is channel. That will help keep the cyano under control, but make sure that you also have all your other ducks in a row like PO4, pH, Alk, etc. Excess CO2 is a concern as well for cyano control
So too much o2 is bad....did not know that! Have a air pump in it because my tank is at the end of the hall with no breeze was afraid I would have pH issues