Absolutely not, they do not need live and most recommend against it.
The issue with live, or concern, is that any live fish that you feed could be carrying something that your snakehead catches not a good way to loose a prized fish, you could QT feeders before hand to get past this but it means extra tanks and then buying food to feed the feeders in the mean time. A lot of extra cost with no benefit. If your going to go with live feeders as part of the diet i'd recommend a breeding tank with a few cichlids instead of a QT, they are a healthier choice and breed rapidly, no risk of disease if you bred your own.
As for options , chopped shrimp , smelt, talapia etc. are all fine they will except most meaty foods, insects are another option and its eas to breed them yourself. Cockroaches, crickets, meal worms are all popular choices. Mine get a steady supply of june bugs in the spring and grass hoppers in the summer. Like most fish they also enjoy a good meal of earth worms as well.
Pellets of any kind will work also, the thought that snakeheads don't like pellets is a complete myth. they will eat pellets of any kind. I've started juvie fry on pellets , I've also had fresh imports eat them first try.
In my experience once they have settled in channa will eat ANYTHING that you put in the tank to feed them. They are not picky eaters at all. As for how much to feed and what the best diet is it really depends on the species not all snakehead species are the same.
If your dealing with a piscivore species like Micro, diplo or pleuro's then then I'd recommend a mixture of chopped meaty foods (shrimp smelt etc) with pellets to help balance the diet.
For other species epically the auranti/gachua/bleheri complex I would feed mostly insects (i gut load mine with fresh veggies before a feeding) , and again pellets as filler/booster from time to time.
This is how I feed mine ,with the addition of an occasional live treat from time to time when I have to cull fry or knock the population down in my Mbuna tank. If/when you decide on a specific species it'll be easier to make recommendations on care!