Resistance Gear (Hydross)

So ive been working my way up into a regular raidspot now, and am the tankadin of our guild, which is currently working on vashj and kael'thas.
The raidleader has now asked me to start farming some frost and nature resistance gear for future Hydross kills so that i can actually tank on that fight (or can i..), but i am slightly sceptical because of the simple fact that i cant block elemental damage, meaning my threat would take a big hit when trying to tank anything on that fight, due to no holy shield/BoSanct.

So, for more experienced tankadins out there, are we viable tanks on resist fights? If so, what kind of level of gear do you guys use for it (im mainly thinking Hydross here)?

Also, if i understand correctly, elemental damage cant crush, but can crit, is that correct?

Cheers in advance.
_________________

(if the figures are terrible, im in my loldps gear, obviously)

There are already a number of threads on the hydross fight and how to gear for it in the SSC forum