hello listers

I'm back with my old i386 box and have a few questions. I have 
netbsd-2.0_BETA installed on the second half of a 6 GB second hard drive.

1. How much space is required to recompile kernel and userland? (I have 
a GENERIC kernel in at the moment.) I don't think I have enough space - 
after downloading the src files /usr is almost full and / is about 22% 
full. My swap partition is about 750 MB. (I am using the CD 
installation's default partitioning.)

2. Is it possible to wipe Linux off the first part of the drive and use 
that for the NetBSD installation?

3. Is there any other way to free up more space?

I don't have a CD with me so can't go down that route.

Thanks in advance for your advice.

Ja'far