So pretty soon I will be getting an OD to put on my board and putting my HD500 in the FX loop of my VH100R to use delays, tremolo, volume and noise gate in the loop. I currently have those things in the loop already with the 4 cable method in the insert loop. I have a few questions about it though. Any insight is useful.

1) My FX loop compared to the insert loop is very loud. Like the volume coming out of the amp is about twice as loud. Can I use the POD's master volume as an attenuator of sorts?

2) If I have the volume pedal in the insert loop at 0 there is still a bit of thin, can of bees type noise coming out of the speakers when I play. Will this go away in the fx loop?

3) Each channel has an effects knob to adjust the amount of signal going into the FX loop, for maximum usage of the volume and other effects would I just keep this at 10?
Gibson RD Silverburst w/ Lace Dissonant Aggressors (SOLD)
Electra Omega Prime Ceruse
Fender Franken-Jag Bass

Amps and the like:
Laney VH100R
Seismic Luke 2x12
Dunlop 105Q Wah
Gojira FX 808
Line 6 M9