1, James Swallow's Red Fury has the Flesh Tearers using a whirlwind so there is some precedent. While the Flesh Tearers are limited in terms of equipment and resources i would think it likely that they would posses some whirlwinds given that's its based on the relatively common rhino/predator chasis. I don't imagine however that they have many Storm Ravens, Land Speeders or Land Raiders, rare vehicles which are harder to maintain.
2, It would be better to represent Moriar with a Death Comapny dreadnought as that's what he was. He's always been gripped by the red thirst and been frenzied. It also makes sense thematically to field some death company in a Flesh Tearers list as they are more susceptible to it and have been decimated by the condition.