I have a couple of the axe023, and I was wondering about their full potential. Are they compatible with IR sensors? What else besides bumper switches and simple motors can you use them for? It would be fun to make a bunch of little robots.
To put it short; RTFM :)The
To put it short; RTFM 
The answer could be sooo long - it is all in the manual. Ask specific questions to get precise answers, please. If you ask "What can I do with this chip?" you get a fuzzty answer
After using 4 pins to attach 2 motors, what have you left? One pin, right? Or 2? Please read the manual.
IR return what? Analouge signals.
Can the pin(s) you have recieve analouge signals? RTFM. If so, yes, you can hook up an IR…
BUT… as I wrote in the "little8"-tutorial; You have an extremely limited amount of space in these Picaxe 8-chips (not Picaxe8M, even). I doubt that you can make any program that can make any use of an input - you will run out of code-lines before you even get started.
Start playign with them 
Start playign with them Hook something up and see what happens. If you still have outputs left hook something else up. Once you get something going it is much easier to help. You’re in the same boat I was in a couple months ago. I tend to want to know everything I can about something before I start. I hate to mess things up. Just jump in with both feet and splash around. EVERYONE IN THE POOL WOOHOO!!