Circulation should be pointed down back wall at subtrate. This pushes micro currents into substrate which carry gases to keep bio activity in substrate high as well as circulatiing ferts into substrate to make them available for CEC binding sites.
With those 2 canister I’d put 160gph new one on spray down back wall. The 600 at 264gh I’d split to 2 nozzles in top corners pushing 130gph around front of tank from both ends, these will make a down draft when they hit front glass creating a nice gentle current along front of tank keeping front half of substrate bed saturated with gases and nutrients. In tank that’s 18” front to back you pretty much need to set up circulation patterns that cover front edge and back edge as well as end to end. If you set up circulation patterns properly substrate bed and plants are really all the bio filter a planted tank needs. Harder currents will be just in top corners or gently sweeping down glass at front and back, except for right in front of nozzles whole center area of tank will be nice calm current Angels will have no problem swimming in.
Glass is a pain to keep clean but it does slow down evaporation. A dirty piece of glass can easily rob you of 20% of light from reaching tank. That means scrubbing it clean weekly with oxalix acid etc..
1/2” under glass is fine for air gap. A 1” strip along back edge is plenty to allow proper gas exchange.
If you do need glass for jump protection these PVC gutter guards are dirt cheap, just cut down to 2” or so and mount to back edge of glass and cut out around plumbing going into tank. Jump protection but still allows tank to breath properly.
For return nozzles nothing beats these. Run flare nozzle vertical and you’ll get nice surface ripple at top for proper gas exchange and lower portion of jet will be pushing water down slightly and into glass making down draft along front. Just angle them about 5-8° in from corners.
Make sure to get right size your hosing. These are 5/8-3/4 hose model (probably what you need) , there also 3/4-1” sized ones.
Input strainers mount just to inside of 2 nozzles in corners. With sweep down center back wall and other 2 nozzle making dual rotating currents in tank that area is where most debris will settle so you get optimal pickup of detritus with inputs there.