//e disk density question

[sdevious@mcs.net (Sdevious)]

I am totally new to the apple, and just got a //e (The Enhenced Enhenced
model with the light case,numeric keypad, and extra 64k memory) and it has
a pair of disk drives (they connect to a card in the first slot on the
right) that I am confused about.  These drives are both the lighter
(almost white) color and seem to be the same 5 1/2 drives used on the GS. 
My problem is that I can't read many of the //e disks I've come across. 
All of the software I have that lacks the little notch on the top right
side of the disk won't boot the computer.  I assume that these disks are
low density and that my newer drives are high density and won't recgonize
them.  Am I correct?  Also, in examining the system, I noticed a pair of
connectors in the back between the video output and the paddle connector,
these are marked with an icon that looks to me like an audio tape.  Could
these be sound in and out or are they for a disk drive?  I would be very
grateful if anyone can help me boot the low density disks, and let me know
about those ports.  I could also use some help finding some basic
information on how to opperate the apple. (DOS commands, a starter guide,
or anything else)  Thank you very much,

Mike
(Despite my questions, I love the apple already)