Help! Some textures going blurry, also packaged level will not open

I am a student studying CGI and making my first game level. I have been a little ambitious with my map size (around a Km squared) and therefore believe that the problem might be that my texture streaming pool (which is showing up top left in red when simulating the game) is causing textures to go to some primitive form. I learned later on in the project that textures should all be square which I believe could cause problems with LOD’s. I am using the kite demo for my foliage which is quite resource heavy too.

I have packaged my level as a test and found that when I go to play it I get an error message along the lines of level has not been cooked (will leave screenshot as an attachment).

Any quick response would be greatly appreciated as asking a forum such as this helps improve my overall mark for the unit.

Many thanks,