AVR-Chat

>
>1) There are a mind boggling number to choose from (transistor, 
>darlington, fet,
>etc.).  Can you give me some guidance as to a 'general purpose' device for 
>this
>type of use and what general conditions the device would not be suitable.

Each type has it's strengths.
Two things to look at carefully, are speed, and current transfer ratio.
Most are relatively slow, and have a ctr that results in less output 
current than is put in.  There are exceptions to both rules.

>2) If driving a low current PC board relay is it good practice to connect the
>coil directly to the AVR (w/snubber diode) or should I use a opto here too?

I don't think you need an opto, but I'd definitely use a transistor.

>3) I think I've seen reference to "opto-isolators" and "opto-couplers".  I
>assume these terms refer to the same device?

More or less.