If you have already set up instant messaging somewhere else, the spaces are for you to display your contact information. Much the same as a telephone number; you don't set it up here; you just display it so others can call you. If you value your privacy, don't bother. The spammers even know how to send instant messages (IMs) to you. There are 3 primary instant message systems: AOL, MS and ICQ. Some people use all 3. I don't use any. I hate being interrupted by someone who wants to chat; it's worse than the phone.
The Google Spider is crawling through the web searching for new stuff. Ever wonder how, when you do a Google search, they know where everything is? That's because they send out armies of spiders to crawl through the web sites and remember everything they see. Some other search engines use robots, which they call "bots".
Seriously, the "spiders" and "bots" are simply nicknames for automated software that surfs the web under control of a computer and sends back text and images of what it finds. The computers back at home base then evaluate the information, sort it and index it, and it becomes part of the search data base.
I think of them as ants out in search of new food supplies, which they report back to the anthill, and thousands of ants pour out.