1. About the size of a bowling ball, intended to act as a frame grade weapon but unable to meet its own energy needs. The numbers probably need softening a bit.
2. About the same as a couch.
3. Not long; it is an excellent weapon but its magazine is tiny: It has no powerplant of its own, only a capacitor and energy transfer and as such has next to no independence of any kind for more than a few seconds, or in direct support of a larger platform as mounted or remote equipment for it. Its meant either to be used for interior security as a drone inside a starship or rigged to a powered frame. It isn't really meant to act with much in the way of independence: It can move for a long time but it runs out of ammunition super super fast.
4. Quite weak, actually. Concentrated fire from a minigun would cripple it within a few seconds of sustained shot. To be tough, it would need some sort of armored glove which in turn would remove its ability to transform, acting only really as a basic hand. To this end, I like this idea of "taking the gloves off" when whatever's mounting it "means business".
5. You couldn't deploy this independently. It would run out of ammunition very quickly and be too vulnerable. Think of it as how a pawn works in respect to more important chess pieces: its function is as a support weapon.