Indeed. If the cooling coil isn't fully submerged in your beer it won't be as effective. I'd expect a 5 gallon batch to only partially cover the cooling coil.

16 inches anvilbrewing DOT com/14-gallon-crucible

I wouldn’t recommend it. It feels a little too tipsy to me so I built a wide base with casters and secured the legs of the fermenter to that base. Now it feels more secure and is mobile.

You definitely could add a sight glass by using a TC tee on the bottom port and the airlock fitting on the lid and connect them with some type of translucent tubing. Usually this is not recommended for fermenters since it is a very tricky thing to clean and maintain sanitary conditions with more accessories added to a fermenter.

This fermenter is not rated for pressurizing. This generally means you can transfer from the fermenter under a small amount of pressure (up to 5 psi) but you will not be able to sustain pressure during fermentation (spunding) or carbonate inside this fermenter.