some really stupid questions

[a.e.nelson]

ok, since I'm new to synth building, I need to ask some stupid questions
so I quit wondering.  First of all, and this is really basic, what are
the purposes of three lugs on potentiometers?  In schematics I've seen,
two of the lugs are usually connected to the same point.  Also, what's
the difference between 'linear' and 'audio' pots?  And which should be
used in synth construction?
One last question...What is the deal with the ASM-1?  Where are 
schematics available?...are pcb's available for this?

thanks
tony nelson