Hmm, i never go with precompiled packages, except for stage3 install optimized for my hardware, as its all the same stuff anyways, installed with the same flags i want, not to mention that in a month of updates it will all be recompiled anyways.
My best result is about 2.5 hours with custom kernel config and compilation, starting from stage3 and going forward. Of course that's only for the system. KDE compilation takes a LONG, LONG time, expect at least 10 hours from start to end, even on the best hardware. But again we are talking about compilations.
To answer your question if its easy to install Gentoo: Yes it is VERY easy to install gentoo and the only thing that might give you pause is kernel compilation. To install: go to www.gentoo.org,
print out the latest version of gentoo handbook document (be prepared, that thing is 100 pages, even if most of it is stuffing), read it and follow the instructions LINE BY LINE, even if it sais to skip to the next part, still at least read through that section. A good example of something that can be easily skipped: hotplug installation, which i find essential for any install, but its only mentioned in genkernel chapter.