First off, there are 3 talants that you always take as a tanking DK First one in each tier. So your friend with 30% parry and 21% dodge is that before or after Blade Barrier.. if its after, his avoidance is abit low, maybe regem to get more avoidance? There isnt rly any need to have more then 30k hp unbuffed in Frost Presence. In raid you will get about 37k buffed or so. Try to work in gems to flatten out the avoidance abit.
When it comes to Singletarget tanking its nothing more then bash yourhead to the keyboard and the magic will happend.. or well its little more advanced then that but not much. I usualy go with IT PS BS BS OB, OB OB IT PS.
on AoE i always start with DnD IT PS PL this since DnD does massive amount of Threat
Icy talons is a flavour thing, i use it. Someone may not its more or less your playstyle. Plus its a raidbuff which ofc is very nice. The KM is set to a 5ppm now so it rly doesnt matter how fast you hit you will only get around 5 proccs per minute from it.