To begin with, yes, it is all possible, and shouldn't be terribly difficult. However, if you mess with the sources.list file, your LMCE system will attempt to update a bunch of stuff automatically, that will break the installation (Believe me, I did it... Whooopsie!!). Install what you need from .deb files, or compile from source, rather than using apt-get / Synaptic / Adept, so as to prevent this issue.
I'm not terribly sure if FTP is present by default, but the whole system, AFAIK, is BUILT on MySQL, and includes HTTP server. Probably PHP as well, as when I installed and used phpmyadmin upon mine, it required NO dependencies, gave no errors, worked like a charm. Simply went to
http://localhost/phpmyadmin, and it came right up...
As far as torrent client, again, I don't know if there is one installed by default, but I installed azureus without problems, and have used it on my core, so it is definitely possible. As far as a web-based one, again, the system is already in place for it, so with a bit of config it should work...
The only thing I can see being a potential issue for you, with your self-stated lack of expertise with Linux, MIGHT be the fact that there would be some config necessary to make sure that your public HTTP directories are separate from the admin pages for the LMCE system, and whatever else...
Sounds like you're trying to do something very similar to what I have planned for my own server, creating a complete, do-it-all server for the house, so I'll definitely keep an eye on this thread, and help where I can!! Keep posted as to how it goes...
