Say I make a .hmp terrain file in MED. Then I load it into WED and add details like add rock.mdl and save it as .wmb.
Now in the code I am loading the file as a .wmb. Will I still get the benefits of the chunked terrain?
or do I have to load it as a .hmp file in the code to get the chunked benefits?

Kinda wondering if after the .hmp is loaded into WED and then resaved am I loosing the chunked terrain benefits? I am just little unclear on this.
thanks

You would load your level file, level.wmb for example, it when then load your hmp and the mdls and everything else in the level. You are not losing anything as a hmp is not a levle file and can not be loaded as one, it can only be loaded into a level.