Jos,
You seriously sound like you have your 'ducks in a row' -
The bad thing is, that my amp could probably blow a hole through a wall at 4 or 5

... I've never had to turn it past 3 or 3 'n 1/2 for a show consisting of about 300 to 1,000 people. (micing it with an sm57, of course) ... bad choice of amp, yes...?
I'll reset all my Quattro knobs 'n give the whole thing a new start like you suggest - I do seem to get a bit trebley at times
The reason I think I needed a boost pedal is because I've been using either my drive 2 and/or compressor for soloing, when I really just regularly need them throughout a song - maybe if I don't try to get the extra volume out of my compressor for a solo, then I won't have feedback problems?
HOLY COW! No, your not crazy. You made me think about it, and yes, I pick much harder at practice... Yes! I've noticed that about compression... and you'll haveta excuse my lack of knowledge about it - I bought my Quattro about a year ago, and only started using the compressor towards the later half... but yes, I noticed that I could strum the fire outta my strings, or pluck a note really softly, 'n it's all relatively the same volume while compressed! - So I'll make a conscious effort on the lighter picking.
Ahh see I own a Tele now so, I keep my volume knob all the way up now (for being afraid of tone loss, right?)... should I do that by the way? - I've always used a Les Paul with my vol. knobs around 5 or 6 'til a solo/etc hit. So this whole Tele setup (even though is awesomely simple) is still new to me
Have you ever had the THD Hot Plates to cause any damage/effect your amp?
Our first gig of the season if this Saturday - I'll give all of this a shot 'n get back with ya - I can't thank you enough for sharing your knowledge.