For the cloaking technology, I thought of it much like an old CRT compared to a modern LCD, the modern cloaks do not get disrupted by any debris or shrapnel and make the Predator closer to translucent than Feral's cloaking, but sacrifice the ability to function in water for that.
As for the Netgun, even in Predator 2 it quickly cuts away from the first victim we see trapped by it after a second or so, so what happens after that's up to interpretation, and later through the power of the plot Mike Harrigan survives under it long enough for the disc to ultimately release him.
Maybe City Hunter had it a bit slack or something in that particular instance. Jungle Hunter in Predator only used a Plasma caster and wrist blades so we have not seen it since then I believe.