I guess I'm not so expert like you, but when I did my installation I was really a beginner,
I was a complete Linux noob when I first installed Gentoo as well. I've been using it for about 7 months, so I'm hardly an expert, but I know enough now that I felt that I could organize my system in an educated way.
Is it good to have so many partitions?
From the reading I have done on Gentoo.org among other sites, it is safer, improves performance, and makes fsck faster--especially with ext3 which runs a check every 30 mounts or so. Plus, I like the organization aspect.
I never heard about some things you mentioned: portage overlay, nptonly and modular Xorg... can you give me some info?
Portage overlay allows you to download ebuilds that are not in Portage for things like Firefox 1.5, kernel patchsets, and other software that are not stable enough yet to be included in Portage. Usually, those ebuilds go into /usr/local/portage and are not affected by emerge --sync. The overlay directory is expressed in make.conf with this line:
I chose to make mine:
There are two methods to do multi-threading under linux. Linux Threads is the old way and NPTL is the new way. In order to use the new threading method, you have to specify nptl or nptlonly in your USE flags in make.conf. Using the nptl flag will cause 2 versions of glibc to be built--one of nptl and one for linux threads. This method does not work on the PPC with the current version of glibc for some reason. Nptlonly will cause only one version of glibc to be built and it works on the PPC, but there are a few packages to don't play nice when built with the nptlonly glibc.
The modular Xorg is the new way Xorg is going to be distributed starting with 7.0. They decided to divide Xorg into separate modules so that development management is easier. I assume it'll also allow you to install those modules you need and reject the ones you don't. I could not make 7.0 work on my machine because there are still too many ebuilds that do not have the ~ppc keyword. I hacked a bunch of ebuilds to include the keyword, but I guess I didn't hack enough of them.
Xorg 6.9 is the last monolithic version and is meant to be a transitional release. There is not an official Gentoo ebuild for 6.9. I found one in the forums and stuck it in my overlay directory.
Would it be possible to make a complete stage1 installation using gcc-4.0? And how can I tell portage to unmask it? I tried, but unsuccessfully
I'm not sure if you can do it or not. I have not messed with 4.0 and the current suggestion seems to be to have it installed along side with 3.4. Gcc-4.0 is not really stable yet.
To unmask it, you can try this as root:
echo ">=sys-devel/gcc-4 -*" >> /etc/portage/package.keywords"
What about these "exa modules"? Where can I find them? How to use them?
I don't know enough about exa to give you a good explanation. All I know is that the Radeon cards below the 9600's can use the new module and it finally makes shadows and (maybe) transparency usable. I still have not had a problem with exa, but I still have not played with xcompmgr.
What kernel did you use?
Currently, I'm using 2.6.14 with the acid2 patchset which adds a different CPU scheduler, fbsplash, and a few other things. You can read more about it here.
I also use the SFS patch so I can read my MorphOS drive.
I hope this helps.