I used an NS-50 for a while, which worked well. This is how you usually use a gate with trigger (which is the same as a compressor's sidechain) in and out and a loop:
Don't put anything in between the guitar and the input (especially dynamics effects like compressors and limiters) - the noise gate "follows" the envelope of the guitar signal and you'll throw off the trigger. Any dynamic effects, drives, modulation and EQ in the loop. Digital time-based (Delays and reverbs) and pitch-based effects (pitch shifters, harmonisers) after the loop (although they can go in the loop if you need them in front of a drive pedal or something).
If you use delays or reverb in front of the amp, you don't want to include the amp's preamp in the loop, as you'll chop off the reverb and delay tails. You can also only use the NS-2 at instrument level (-20dB), so if your loop is running line level (a whacking +4dB), you can damage the NS-2. Some modern amps can run their loops at instrument level - then you can do it and still put your delay and reverb after the noise gate loop.
