Dargor, there's no need to have the Telvanni work on creating slime creatures, we already have House Hlaalu for that.
I've probably read 95% or more of the books available in Morrowind, plus a fair number of them from Oblivion, and one or two from Daggerfall (extremely limited time with that game). Whether that tops 100, I'm not sure without checking some kind of reference or list, so I chose 50-100.
Most of the time, my characters will read them when it's safe to do so, generally after a site is cleared and it's time to take stock of whatever isn't nailed down (or is, but can be pried loose). A few will be taken off-site and read later.