Documentation: help file should cover some of them, and I can answer most of what it doesn't. Specifics would be nice to have. =)
Tier list: Closest you'll get to one is the one on the now-defunct wiki guide which lists them as:
* High: Blackcomb (highest by a rather wide margin), Primula, 2000 SP1, XP SP3
* Mid: Anthurium, BlackSelena, XP-B, XP, Vienna, Cymmie, Iris, Vista
* Low: 2000 Vanilla, Millennium, MS-98, Millennium-B, Millennium-R
There used to be five tiers, but it was compressed while people were still trying to figure out who would go where - and that never really finished. The order's still roughly correct, though.
Reading material: The wiki guide.
It's not being updated anymore due to interest in the game being pretty much dead, and it still has a few bits of Bootfighter-only related material within, but it should still be serviceable for getting a feel of each mech's playstyle.
Malfunction: Buh? Explain exactly what you mean, as the only case where it'd "malfunction" is when its superlaser doesn't fire, and that simply means you're out of weapon energy.
Servers: The servers themselves don't cost money to join, and you'll have to deal with the translation issue. However, if you're willing to host one yourself, you can actually apply the English patches on a Japanese version of the game to get a mostly-translated version.