I'd stay away from behringer mixers if you can. They just tend to have a reputation as being pretty cheap, and you can really get something better for pretty cheap price too.
The yamaha's seem to be pretty good, or you could go a little bit more for something like a soundcraft.
Another option that would work in place of a mixer is dedicated preamps, such as the audiobuddy or dmp3 from m-audio. The mixer will have preamps built in, but you can get higher quality with dedicated preamps, as basically with a mixer, you're paying for preamps AND all sorts of extra circuitry - which you may or may not want. And if you dont want it, dedicated preamps may be the way to go. They still may cost more to get the same amount of channels, because there aren't many dedicated preamps built as cheaply as the ones in cheap mixers.
Unless you spend a lot more however, a dedicated outboard pre might not be very significant of a step up from the ones in a mixer such as the yamaha mg series, and if you think you might want some of the functionality of a mixer (mixing things down to subgroups, using it for another headphone out for monitoring what's going in), that would be the way to go.
At this point I'd say get at least a solid mixer or a few channels of solid dedicated pre if you can (if you need 2 channels, go with a dmp3, if you need 10 you're gonna pay a lot more than you would with a mixer, and at this point money would probably be better spent on quality mics)
And yeah, you can plug in a guitar or bass either using a direct box (to get it to mic level and balance it, so you'd plug it into a mic input like you would a mic), or an instrument level input if you have something that has it. You probably COULD even plug it in to a 1/4" line input and get enough gain from somewhere to get a signal, but it wouldn't be a very good sounding idea.
Sound cards, I think the suggestion of M-Audio would be a good area to start looking at for your needs. They make some pretty solid entry level type systems that a lot of people seem to really like.
One thing that's really important that often gets overlooked in a recording chain is good monitors... personally I'd just mix with whatever you can at first, because whether you can really hear w hat's going on well is going to be the least of your worries for a while, and if it were me I'd reccomend waiting until you can afford some good quality monitors rather than buying cheap ones right away (Buy cheap, buy twice, is a common saying around here).
Other than that, seems that you have a pretty good idea of where you want to start. The selection of mics you listed will get you by just fine for quite a while (you could even get a pair of condensers for overheads that would also be useful on vocals.) That will cover a drumset just fine for most things, and everything else is even less demanding on mics than a drumset. A few quality mics will beat an arsenal of crappy ones any day. Heck, one quality mic would beat an arsenal of crap mics, hehe.
Hope that helps you get a better idea of what you might want to do. Good luck, and be warned: recording is a very fun - and very expensive - hobby.... there's never an end to the cool new things you'll want to buy.... but I like it anyway.
You can use plugins in your recording software (there's even some good free amp sim plugins) to play around with that.
But, as was said, you can get a much better sound by mic'ing your amp (assuming you have at least a decent sounding amp), and you'll learn a lot about mic placement that way too, which will be crucial any time you're using a mic.