ok. as for the pump well the return pump try getting a maxijet 900 or a 1200. replace the stock one. as the stock one always is bad.
for the suction do you mean from were the water enters the chambers in the back? the wholes? if so its not supposed to have that much. since the water levels in both sides are the same.
your water temp is good. but 76 is like what most reef tanks are at. but your ok.
for your heater. try switching the sticky things lol.
for LR try getting more. but it all depends on you and how you want the aquascape.
as for the tester. i bought the one they have in my lfs. so i guess the one they have thats for marine will work.
caves
fish love caves! lol
anything else i might forgotten?
or and remember move the nozzle so your surface water can get movement and wont look like that.