Anything over OS 7.6.1 is going to be pretty unbearable on a 1400. 8.6 might be just bearable but anything on top of that will bog it down. OS 9 with speakable items enabled will be about as fast as a sloth.

There isn't even that much WiFi software for the classic OS. The only classic war-driving software is from Alksoft and that requires the Apple drivers. The Orinoco drivers are pretty useful, and they can actively scan for open nets, so I guess all isn't lost. Plus there are versions of it compatible down to 7.5 IIRC If you want to make a email node then its possible, but websurfing with it will be really slow.

For a robot there used to be some mac robotics sites out there. There used to be some serial controllers as well, but they're really rare. If you can get one of those and have some decent programming skills then you could be able to pull off a mac based robot. There have been attempts at it but I've never seen one completed.

Personally I'd go for a Digital picture frame if you get one with an active matrix display. I hate to break the bubble, and I love older systems, but there isn't a whole lot you can do with a 1400.