I've done quite some reading on the linux filesystem and want to make my box cleaner and more convenient for maintaining.

As I understand a good way to start is to download src to usr/local/src (and rpm to /usr/local/rpm etc). I can only do that as root though. If I download a file in Mandrake 9.1 it refuses to save it at usr/local/src since I have no write access. Shouldn't I be able to do that in all the usr/local folders? Is there an easy way to fix it?

Final question(s): after I've done a succesful compile (it happends) and do a make install can I delete the folder I compiled in? I tried nvtv recently and it only needed a configure and a make (no make install). In the readme it says that I can copy the bin to the folder I want. Nice, but what to do with the rest of the folder in /usr/local/src? can I delete it or move it? Do I have to keep the files in one folder? Quite confusing I have to say....

Regards

usually, non root users don't have write permissions for the /usr and its subdirectories which is generally a good idea - don't wanna accidentally programs, libraries and stuff like that. If you are comfortable with it, you could change permissions for /usr/local./src and such so that you don't have to root to save thigns to them. You can do it from inside konqueror or also with the command
chmod
see the manpage for more details.

In general, it's ok to delete the source code though I think some programs can be uninstalled with make uninstall and for that you'd need the the source files. I don't nvtv needs the stuff in /usr/src. After moving the bin file to /usr/bin or whereever, you could try if it runs ok even if you rename that folder. If so, you can probably get rid of it.

deleting the source/build folder is standard practice. the binaries which are copied or installed should be self-sufficent.

Also, I (and most people I know) usually just build things in their home directory, make install as root, and then delete the build folder. This makes it difficult to uninstall; but you can either
1) keep the tarball, unpack, configure, and "make uninstall" (if you use the same installation folder both time, it should work)
2) use a package management system like GNU stow.

or, like me, never bother uninstalling anything