I use MT v 2.9.42
Are there supported drivers for PCI-Express slot? Exactly for Intel 82571?
Or maybe I can Install them manually?

You cannot install drivers manually,
you may try to test interface with 2.9 version, 3.0 version provides support for more interface, try with 3.0beta10 (if 2.9 does not support).

I don't want to buy PCI-Express card if I will not known 100% what this card will work
Maybe can somethere get full supported driver list for 2.9 (if there are some new drivers in) and for 3.0?

if you want to be sure, use devices from this list only:
http://www.mikrotik.com/testdocs/ros/2. ... erlist.php

but v3 has more drivers, new list not yet made