"Good quality" is a very vague thing where microphones are concerned, and with audio in general. While you can assume that those mics, marketed as they are towards videogames, are likely to be cheaply produced under loose design requirements, it may very well be that those mics are good enough for your purposes. They do work for their games after all, and even the cheapest mics are generally good enough for what people need them for.
If you have two of them already, the best test for whether they'll work for you is just to try them out and see! Make your own recordings and see if you like them.
Regarding your second question, the USB adapter is a built-in audio interface, which performs preamplification and digital conversion. Such processes do have an effect on audio quality, although it can be fairly subtle compared to the characteristics of the mic itself. If you're really asking whether or not you can use it, the answer is "yes." Again, you have it already, so you can just give it a try.