Question about my UR44

So I’ve got it hooked up to a 2013 MBA running Live 8 Intro. I’ve got my MPC1000 running through 5&6, using the mic/line inputs for synthesisers. My problem is that the MPC is very quiet when compared to all other inputs. Is there a way for me to fix it or am I simply doing it wrong?
I’ve also noticed that all old Live sessions I open now play very quietly with lots of hissing noise. Does this have anything to do with the dspMix software that came with the interface?
And lastly, I would quite like to have Ableton control the monitoring of all the devices hooked up to the interface, but even when all channels are set to “monitoring off”, I can hear all of them playing. Turning monitoring on in Live just gives me shitty sounding duplicates.