Is there any way to transfer IW5 files to IW4? I want to use the MP7 from IW5 and put it into IW4. If this is possible, is there a way to make it available for custom classes, not just entering it in the console?

>no experience

Don't even try if you don't know how.

 

Also, I don't think its possible at all.

Nope, not possible. 'Yet' atleast.

No, not possible, all you can do is porting already existing weapons from the SP to the MP.

Have fun both finishing FifthInfinity and Decoupling experiments. At least weapons.clump makes the latter obsolete for future titles.