there are a couple methods.
gentoo is a source based distro - it compiles all packages from source before installing them. so whenever you install a package, it will have to download that package's source tarball. i want to say that tarballs are smaller in general than the equivalent binary package, but it varies.
you can install from an iso. i believe the full iso for the latest release is a little over 400 megs or something - not a full cd. there are three different stage tarballs on the cd that you can install. stage1 is from the absolute beginning, where you download and compile everything. stage2 is where the core programs like gcc and glibc are precompiled and extracted off of the cd, and the rest of the system is downloaded and compiled. stage3 is essentially a full working system extracted from a tar, so you don't have to download any packages to get a basic system up.
but you are going to have to download stuff regardless; gentoo is a rather net-oriented distro. the full install doesn't come with x, for example, so you would have to download the x sources and compile them. the advantage is that you can download and compile the specific packages that you want - you don't have to waste that bandwidth downloading those extra programs on the cd that you'll never use.
i recommend checking out the excellent x86 install guide on gentoo.org to get an idea.
i don't really know about talking to the developers. maybe, but that's specifically what they put those boot options on the cd for - computers like ours that have problems with certain components. i'm pretty sure we're not the only ones, and there could very well be too many for them to fix. but of course, i'm not a developer, so i don't really know. and since almost all distros have the problem, it seems like it's more a problem with sager than linux. maybe the way they build their laptops is weird.
and on that note, with the gentoo iso, you have to pass the 'nodetect' boot parameter to the cd or else it will hang on autodetection like the other distros. just so you know.