The dirt texture is actually a pretty simple effect- It's actually just a photo I took of some gravel that's been put on a layer set to 'overlay'. Trying to use hydraulics for the legs would be too bulky and fragile, so if I had to guess I'd say they're probably moved by muscle-like bundles of an electroactive polymer of some sort.
No that's actually just Photoshop 7. There's just a dirt texture put on between a layer of relatively flat color and most of the brushwork. It has some potential, but I'm not totally happy with the effect as executed.
Ah good, you've found the color palette in Photoshop. It looks much better, especially with some shadows too. Obviousely you could go into texturing it and making the shading smooth and getting rid of obvious brush marks, but it all depends on how much you wanna spend on it.
Your drawing ideas are usually very good, so I don't think the shading was ever a problem. You could try adding some glows on shiny metallic parts (simple color select + feather and fill with white) - don't forget Photoshop isn't just about editing images and digital painting...you're free to use any other effects, filters, textures, etc. to complement your painting.
The problems of traction and ground pressure present some interesting problems with a walking tank design. Hooks can look great, but if you have it marching around on anything too pointy it'll look weightless and like it should be digging into the ground more. I'll probably do something along the lines of having some sort of rubble cleat that can be flipped out for climbing, but is normally folded back. It should give the visual impression that it's walking on its knuckles.
This one is based on the old Renault FT-17 from WWI in terms of crew and general layout: Just a driver and gunner/commander. Most modern MBTs have a crew of four (driver, commander, gunner, and loader) though later Russian tanks dispensed with the loader in favor of a hydraulic autoloader to reduce the interior volume of the turret (and hence the size of the vehicle).
I didn't really think too much about the specifics, but that sounds about right. The bow gun is probably a .30 instead of a .50 though, due to the size of the weapon. It's just to keep enemy infantry from getting too uppity anyhow.
It's small, but keep in mind that only the gunner's upper torso is in the turret. He's either standing on the floor on sitting on a jump seat extending from the turret ring. Being mounted in exterior barbettes, there are no gun breeches to get in the way as well.