Vasuda and vasudans are names assigned by Terran linguists to the language of these aliens. Much like Shivans were assigned an arbitrary name.
Obviously every conscious species calls their home planet "Earth", "Water", "Home", or some variant thereof, and space-traveling species would likely assign the names of planets corresponding with the names of the species that originates there, or vice versa. We're from Terra, so we're called Terrans. This group of aliens got an arbitrary name assignment of "Vasudans", so it makes sense for us to call their planet "Vasuda". What, there's more than one habitable planet in the solar system and they have spread to them? Well let's call the original home planet Vasuda Prime then. [Primus = The First, Prime = derivative that can mean "the most important" or "main", you get the idea]
What do Vasudans eat? Well, first of all it's no use trying to establish taxonomical connections to any Terran species; you can find parallel features and resemblances but to our knowledge, Vasudans don't have common ancestry so even trying to estimate their bilogical structure is guessing at best.
However their appearance does give us a couple hints. First of all, they are big. Very big in fact, and from their apparent strength I would estimate their body density is about equal to humans or higher, which means their body mass would probably be something between a gorilla and a bear. Herbivores of that size need to eat almost constantly. Vasudans don't.
Also, Vasudans have two seemingly very well developed eyes that are pointed forwards, which means they have a good stereo vision, which is important for judging distances accurately. Again a trait that is not usually present in exclusive herbivores, but could be explained with stereo vision being important for other reasons than hunting - like grabbing tree branches and stuff, like many tree-dwelling herbivoric species do.
Another thing, Vasudans walk upright. That's an interesting thing to note because upright posture is a rarity in Earth... in fact, apart from bipedal Saurischian dinosaurs and flying dinosaurids [birds], there are few species that mainly relay on their rear limbs for walking/jumping around. Kangaroos come to mind, chimpanzees can do it but usually don't, bears can stay in upright posture for a while but tend to move on all fours. Some rodents jump mainly on their two rear legs, but otherwise most mammals tend to use their all four legs for movement.
If these similar traits to humans can be considered as parallel evolution, then there is a distinct possibility of vasudans sharing similarities in their evolutionary history with humans - which would make them most probably omnivores.
What comes to their biological structure, perhaps the biggest question is whether they have an endoskeleton or exoskeleton. I would guess endoskeleton, since exoskeleton gets difficult to maintain for big animals during their growth to adults; due to the required structural strength, it's usually more efficient to have living tissue over calcium endoskeleton.
This probably doesn't apply to shivans since we have no idea of their evolutionary history, which is bound to be a very special case seeing how they can withstand vacuum of space and operate effectively in zero-g environment, and they have a laser beam they can shoot from their heads, and energy claws not unlike light sabers...
