Hi im wondering what the polygon and texture limitations would be to import an asset into UDK. If anyone could provide me with information or some links to a site with these details it would be great. Its meant to be a LARGE HERO PIECE btw.

It depends on what you use the asset for. If its a big center piece object then you can easily get away with 20k-40k but generaly small stuff i'd stick with below 1k-2k.
most important thing is the silouette. Look at what the minimum number of polygons are that are needed for your model to match the silouette and stick to that number. then where needed add in details with normals maps and textures

This question has been asked a million times, and there is no straight answer, very much depends on the type of assets, and also the type of game what platform your running the game on.

Import stuff until it starts lagging.

I think( not 100% sure) that the max polycounts are:
StaticMesh: 65535 ( 16 bit index)
SkelMesh : 4,294,967,295 ( 32 bit index)

Why would anyone need a 4 mil polygon object in one scene. I mean i bet its better in all respects to have such a big object (if its static) to be broken up to smaller peices.

Well I dont think anyone should have that much, but he asked for the limits and that is the technical limit.
As to why they set that limit, it's probably because 65535 MIGHT not be enough for some crazy characters. The next jump is the 4 million number, since you increase from a 16 bit index to 32bit.

ya like osman said, it;s kinda like ram and the jump from 32bit to 64bit, we had to make the jump since we people were maxing out the memory limitations of 32bit systems, so had to jump to 64bit, which supports so much memory that it will be decades till we even get near it;s hard limitations.

same idea with skeleton meshes allowing up to 4million tris, since in ue2 i beleive they had the same max as static meshes.