Install complete Almost

Well I got the amp and the new component set installed and working.  I do have some amp questions.  I have 3 selections on the amp and 3 dials.  The selections are low pass, flat, amp.  The dials are level, low pass, high pass.  I have Alpine components hooked to the amp.   Us acustics usx2050.

What should my selection be for low pass, flat, amp?

How do I determine what levels to set the Level, low pass and high pass dials?  Should I be able to turn the stereo up to max volume with no distorion?  Or should I peak at the stereo volume like half way up?

Currently I have it set for Amp, and the level almost all the way up.  My hu goes to 35 on the volume scale and I start distorting around 23.  Mostly on the bass side. 

your crossover settings should be set to full range, because the passive crossovers that come with the components should filter what needs to be filtered.

if you are referring to the gains, they should be set to your line voltage from the deck.

Should the amp be set to low pass or flat?

Are gains and level the same thing?

Does the level setting control how much wattage is being produced or is the wattage constant at any level ?

Install is finally completed.  Car is back to orginal condition and I have new and improved sound.  It was a lot more work than what I thought is was going to be.

Thanks all for your help