@LifeinAsia, I do not thing the cost of a desktop OS is not important. Pre-installed Windows is effectively free - the very low OEM Windows license cost is (more than?) offset by getting paid for installing a few promotional things, which is why OS free hardware is no cheaper.
Its different for servers (especially if you are doing things like running lots of small VMs) and if you have enough installs that license tracking compliance starts taking up time and creating risk. I have to admit I was thinking purely in terms of individual webmasters.
@dstiles, regarding 6): it should work if you install an ssh server on your Windows server. You may have to set permissions on transferred files, but that may be necessary with ftp as well - and it is a lot more secure than ftp.
You are, of course, at this stage quite right to keep your Windows server and once you are on Windows 8 you will have a decade to its EOL.
regarding 2). I hardly ever install non-repo apps. I do have three third party repos which will need changing when I do an OS upgrade, but there are only three of them (for MATE desktop, Komodo Edit and Ninja IDE) and I have stopped using one (Ninja).