Yes, the BC-02s are common on eBay and can be had for very little. They fit not only the SW and SWII but also a bunch of BubbleJets including the portable model (I had one for a few years but dumped it because I had no real use for it).
I recommend the LaserWriter 16/600 PS. It's large but it's also fast and produces great quality prints. You can also network it to a newer computer if you've got one nearby--I'm thinking of putting it on my iBook as well as the Plus I use it on.
The ImageWriter II can also be networked and if you're going to be printing multipart documents (i.e. banners) I suggest the use of one. If word processing is your main objective, though, I wouldn't recommend an IW.
As far as what Mac to get...
I use a Plus for word processing and page layout. It works fairly well with 4MB of RAM, System 6, and an 80MB hard drive. It won't win any speed contests but it won't lose them either. On a Plus the drive has to be external. If you find an enclosure, you'd be best replacing the drive with a fast one. I use a Quantum ProDrive LPS on mine, you may be able to swap with someone on this site in our trading post section for one that was pulled from an LC (common in those machines).
The Classic and SE are marginally faster than the Plus. You can get one with an internal hard drive and in some cases, a high density floppy drive (any SE made after August 1, 1989 and all Classics have them).
An SE/30 is tougher to come by for cheap. You may have to pay extra but it's worth it for the speed. Classic IIs aren't quite as fast but they're nice for a little speed increase.
If you want to get a Mac II series or LC series, note that you will need to buy a monitor. I recommend an Apple monitor to match it--the 13" displays are Trinitron technology and the shadow mask 12" RGB fits perfectly on top of an LC. Any II, IIx, IIcx, or IIfx will need a video card, make sure your machine comes with one.
As far as software--there are many choices for word processing. Some on here love Word 5.1, which you can usually find on eBay. It's harder to find MacWrite Pro there but if you find someone selling it, go for it. ClarisWorks 3.0 or earlier is also a good choice for basic word processing--Word and MacWrite Pro are more advanced. This one's usually a cinch to track down on eBay.
Look for MacDraw II as well--you'll soon find you can't live without it. I also recommend looking for Broderbund's Print Shop (tricky to search for on eBay because so many listings are for the new version, you want the original non-deluxe version) and getting Cliff Johnson's puzzle games from his site (3 in Three will keep you occupied for hours).
If the computer doesn't come with a system, Apple makes 6.0.8 and 7.0.1 available on their site; either should work unless you have a Mac that came out after Summer 1992, in which case you'd want 7.5.3.