Amps, tubes, gutars, picks, your own hands, how old your strings are and the freaking barometer reading all effect your tone. And you have it right. A Groove Tubes "10" is the most stringent, clean tube rating as they test them. If you need a quad of tubes you will need to BUY two more just like them to see what they sound like. I wouldn't advise putting tubes of different current caracteristics in the same amp on the same bias circuit. It would probably be OK (heck, it may even sound good) if you set a happy medium on the bias for the different tubes, but I've never done it so I can't reccommend it.
Yes you should adjust your bias voltage to suit new tubes. The tubes are the amplifiers and they are somewhat variable. The bias is a parameter that these devices (the tubes) rely on to be stable.
You can always sell the "10" tubes (you bought them, someone else will too) and buy some different tubes. I would suggest a matched quad to save time and effort. Do some research as to what tubes sound good in your amp. Guys are going over this info as nausium all over the web. If you decide to stick with Groove Tubes (the only brand AFAIK that has the distortion rating) then you'll need to decide how much power tube distortion you really want. You play a 100 watt amp. Do you crank it? Does it have a master volume that you use? If you don't currently use power tube distortion you have no way of knowing if you'll want more or less. Example, if your currently NOT using your amp in a way that distorts the power tubes but you really want "that crunchy el34 sound" so you get into some low rated Groove Tubes that actually allow you to get a little power tube break up, but it messes up your tone instead of adding something you like. It could also make it so you can't get as loud clean. That could be a problem too. Do you understand what you really want?