Doepfer

Hi- I'm designing my first Doepfer now and have a few general questions about it:

Is the A-119 the only way you can incorporate external audio into the A100 or can you 
patch another synth, for instance into any of the audio inputs? 

Can sound from the Audio Outs of the modules (VCOs, VCAs, ect) be patched directly into 
my home monitors or do you have to use a Mixer module for that?

Finally, I'm not 100% clear on the difference between the Linear and Exponential Mixers 
and VCAs. 

The manuals for the modules lead me to believe one thing but I want to double check 
before I decide exactly what I want/need.

Thanks!