Update on the plane ive reworked quite alot of the textures im planning to reduce the sharpness to the exhaust its abit too sharp and plasticy atm always looking for critique :)
Having intersecting geometry like that is fine, and since this is a very low poly look your're going for you can even do it with more parts of that mesh to get an even lower poly count. As for the sharp edges, do you want the mesh to me smooth for like the round part of the wheels and sharp in other places? or just look…
Wow. The character sculpt looks great. I would watch the sharp edges you've got on that hand gun. They might be too sharp to transfer to enough pixels for the normal map.