I personally stay away from the presets and set up my own patches from scratch. As far as blend settings go I like to dial in dry bass to preserve the low end as most of the effects are just too full on when there's no dry bass in the signal. Just my preference. I use an expression pedal to adjust my wet/dry blend too, the parameters for this are adjustable in the Total menu. In the Global menu, my balance is set to 100%, and I do all the wet/dry adjustments for each patch in the individual effect settings. The best advice I can give is play around with the blend settings until you find what you like.
If you're plugging into an amp go straight into the input, not the effect loop. Use the amp sims anywhere you like. If an amp sim, or any effect, sounds good to you that's all that matters. You can always copy a patch to a different memory slot and play around with different settings without overriding the original patch.
There is an active/passive switch next to the input jack, that should sort out your hot signal.
Have fun