Oh photography... long discussion coming I think.
The more depth of field (which is photographer talk for "whats in focus") you have the better. The higher the "f" number the more you have in focus. The lower the number you have less in focus and some parts of a macro photo will look like less is sharp.
Usually you want to have lights at an angle to your subject to light it completely. So the photos you posted where the flash was on you get more light reflected on even the black areas of the front fenders and therefore you get a more complete view of the subject because you can see the contours of the fenders.
if you don't have flashes you can use continuous lights like bright flood lights to illuminate your subject. I have lights over my track i use to brighten it up that have reflectors on clamps that i bought at Lowes that are just CF bulbs (i think like 75watt equivalent) that have the reflectors around them so when I have done videos for Carrera there's more bright light directed at the track... this also works VERY well and cheaply for taking photos if you don't want to spend the money on flashes or strobes.
I have studio lights that I use that i bought cheaply (for strobes anyway) from B&H. That's the lighting i use for all my slot pix that I post where you see a white background on them. These are the lights I use,not sure if this is the exact kit i bought or not since it was about 6 years ago i got these:
http://www.bhphotovideo.com/c/product/4 ... ftbox.htmlBut as i said you can use worklights on clamps with normal bulbs to do nearly the same thing. They get hot though which is a downside to using continuous lights for photography.
http://www.lowes.com/ProductDisplay?par ... &cId=PDIO1