Most self managed hosting accounts don't offer a full graphical user interface as you have on Ubuntu. But they often have the option to let you use a graphical control panel via a browser which allowes you to do most common administrative tasks over a GUI.

You should install the server version of Ubuntu if you want to replicate unmanaged hosting. Desktop version will work too, just use terminal to do all your stuff.
I use Ubuntu server installed in Windows 7 as a virtual machine in VMware player & use putty to connect to it, just like a real web hosting server. works really well as a development server.

I have it on Win 7 / Virtual Box also.

1) Would it make more sense to start learning the regular version and then switch to Server, or it doesnt matter?
2) Is it ok to get 64bit for both editions (I've seen 32 as recommended somewhere etc, not sure why)

Thank you.

You should probably either learn how to admin through the command line, or use a whatever web control panel comes with the hosting.

There are other options, none of them great. If you're running linux on both your desktop and server there's additional options. That's what I do, but in the end I still do most stuff at the command line.

For what I am trying to do the choices come down to:

Centos
Fedora
Debian
Red Hat
Ubuntu

All server editions. I was told not to get Ubuntu Server, because the root is disabled by default (it can be changed, but it is not recommended). I know I need to spend some time to figure it all out, but I dont want to get into something and then have to swith etc.

I am gonna need to install programs like:

MySql
Imagemagick
Mencoder (doesnt work with 64bit)
Ffmpeg
Flvtool
Qt-faststart
PHP

and use it as development / testing environment on Win7.

Thank you.

Webmin will allow you to do a lot of admin stuff via any browser.

Make sure you use the ssl version and try and change the port number from the default.