I'm creating a house mod, but I have a serious problem

[DavideMitra]

I'm creating an house mod, the house is located in Whiterun, WIND District.

This is my first house mod.

 

When I set the mod as active, some streets of the Whiterun PLAIN District disappear, also, there are some missing textures (always in the Plain District).

When I remove the mod from the active mods list, Whiterun returns as normal as usual, there are no more problems of meshes and textures.

What is the problem?

 

 

 

 

There is also another problem...I inserted a lot of static objects (like columns), and all of them have the same id.

I have created another mod (if modified some people's race), but the CK edited himself the ids of the npcs.

In this case, the CK doesn't show me an id error...so I must to change the ids..manually.

How do I do this? How can I know that the new id I'm using has been not already used?