First silly nit picky stuff, linux is a kernel (the core of an operating system), when this kernel is packaged with other software by a maintainer it is then called a "distribution" or distro. Red hat is a fine distro, there are many other fine distros.
The domain controller is possible, using ldap for a directory is doable, but using ldap (active directory) for windows software distribution I'm a little sketchy on. I have never used AD for that in windows so how it works is a little foreign to me. I believe you could still set up an SMS server (seperate of your domain controller) for software distribution, with or without AD.
Howtos will depend greatly on the distro you choose. If you havent used linux much, I suggest trying a few distros first at home and buying o'reily's linux in nutshell. Get a good feel for the unix'ish way linux distros do things before tackling the tasks you set out for yourself above.
The distro that impressed me most with their support for PDC/AD-- is Suse. Yast makes setting up the services you asked for reasonably easy.
Suse
A place to read about distros.
Have fun
:)