New to blender, having trouble with UV mapping.

Hi! I have a few questions if anyone knows how to answer them, mostly to do with UV mapping. I am currently working on models to go into a game. I created sculpts of my objects using zbrush and then exported them as OBJ’s to blender.
-The first issue is that although i merged the objects to be one before exporting they turn up in blender in separate groups and I’m not sure how to move them into the same group or even merge them.

UV ISSUES:
I have unwrapped a few objects, some with seams and some just using the unwrap feature.
I export them as a png so that i may work on them but when i bring them back in i cannot get them to sit correctly on the model.
-However (I’ve followed at least 8 tutorials and gotten the same result) it renders with the UV map image on every face rather than as a whole image. Does anyone know how to stop that? Do i have some setting wrong that i can’t find?

The attached image was a test so it was meant to be just blue and white (the lid being flat blue the bottom being flat white)


-My other problem is with exporting to unity, the obj wont open at all! When i have it under assets and click it just opens blender again.

If anyone can help me with even one of these issues it would be a massive help as I’ve been stuck on this for a while now…

Thanks!

it renders with the UV map image on every face rather than as a whole image. Does anyone know how to stop that? Do i have some setting wrong that i can’t find?
How about showing us what settings you are using along . Have you set the texture mapping to UVs. Also supply
your blend file and texture file.
Pack any textures in the blend (File External Data menu), then upload blend file to http://www.pasteall.org/blend/ and tell us the download link

-The first issue is that although i merged the objects to be one before exporting they turn up in blender in separate groups and I’m not sure how to move them into the same group or even merge them.
Are you saying they are different objects and you want to join them into one single object. Ctrl+J joins selected objects