=>        Can someone tell me how many AD/DA's the PIC has and how
 => much memory it can easily support?

My databook is pretty old, but neither it nor the PIC FAQ mentions
devices with A/D or D/A capability.  (You can fake D/A by toggling an
output line, varying the duty cycle, and filtering it.)  There are
several different types of PICs, and they have RAM/ROM/IO-line specs
ranging from 24/512/12 to 480/8K/33.  (RAM is in *short* supply, but
you can always add one of Microchip's serial RAMs for external
storage.  You could even add a regular RAM, but it would eat up a lot
of I/O lines.)

 =>        I am thinking about building a data acquisition system for a radio
 =>control airplane. I want to record altitude, airspeed, temperature, engine
 =>rpm, and if things go really well, to use the PWM features of whatever
 =>chip I choose to actually aid in piloting the plane....

I'm currently designing a flight instrument (for paragliding) around a
PIC16C84.  It'll have an altimeter, thermometer, real-time clock,
lift/sink audio alert, and an RS232 port for downloading info to a PC.
I think I'm going to have a lot of trouble getting all the software
into the 1K EEPROM, and I *know* I'm going to have a lot of trouble
making the 13 I/O pins suffice -- the RS232 may have to go.

I had originally planned to use the HC05 or HC11 for this, but you
can't get 'em.  At least, I couldn't.  And now that I've gone to the
trouble of building a programmer and writing a simulator, I'm going to
at least give the 16C84 a try.

regards,
d.