New to Debian

[debian@toursbymexico.com]

Hello

I'm new to Debian, have used Slackware for years but latest release was a
mess so I decided to move to Debian and give it a try, however I have some
doubts and need to complete my configuration to keep working while
learning to use this new distro, so these are my current doubts:

1) How can I disable the graphical login and/or avoid X11 to start
automatically? I can't install the nVidia driver since it tells me to stop
X11 before. And, is it possible to leave it that way, just with the simple
text consoles, and start X11 manually when required?

2) How can I install KDE? Currently it is running with Gnome... I've just
download all 5 DVDs plus the updates one... the gnome (un)install shows
most KDE applications to install, but not the full window manager... and,
once installed, is it safe to remove Gnome to free disk space? Just the
window manager, not its libraries that should break some dependencies if
deleted.

3) There are some programs/drivers that independently of the distro, I
prefer to install them by hand from sources. Does it affect in some way if
I do this? The most common ones are kernel, MySQL, msn, irc, some
multimedia stuff, etc. but at least the kernel and MySQL that I don't like
to use packages for them...

4) Is it possible to install LILO instead of GRUB? I know it is better and
advanced, but I like LILO... would it be safe to install it without
breaking some kind of dependence?

Well, that's enough by now, today I need at least to setup the nVidia
driver and hopefully the latest kernel (no matter if it is GRUB by now)...

Thanks for your help,

Miguel