model is looing pretty sweet

the renders that coldwave does are called ambient occlusion renders.
you can either use the render layers to get it or assign a mia_amb_occlusion node in the textures tab of the mental ray nodes in the hypershade (you need to switch to them in the panel on the left)

you can only do it with raytracing because it relies on it (if it doesn't make sense then find out what ambient occlusion means and what ray tracing is and all will be clear)

14k triangles isn't much, but if you plan to put this in an animation then for what it is it's probably getting on the high end and so you'd fake a bit of the details with texture/bump/normal/displacement mapping, might be a bit advanced for your level though, but doing ambient occlusion renders shouldn't be.

triangles are generally not an ideal way to go but it's not totally harmful and it won't muck up your renders unless you've got them oddly placed. in the end it's just the end result that matters.
for a hard surface model, since it doesn't deform like organics n-sided faces with n > 4 it shouldn't matter too much, but if you get weird gradients in your renders then it's sometimes because you've an n-sided face that isn't planar
quads (4 sided faces) seem to make for better deformations when soft or rigid skinning and it's a lot easier to determine what the toplogy (edge flow) is.

you should show some shots of the wireframe if you're unsure.
click shading > wireframe on shaded then take a screen shot and crop and resize the image