Don't have a pic of the coolant level module but you can't miss it. It's on the passenger side of the radiator about 3 inches below the radiator filler neck. It will be a square component (gray) about 2" X 2" with an electrical connector.
On the air filter depending on your environment, it should be changed out every 3K miles in sync with an oil & filter change. Especially if you live in a dusty environment.
For stock a Fram air filter works good and is economical.
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.