That clears up a lot. First, you can most certainly install Windows after Linux! The problem is Windows will install its bootloader in the MBR. It will not automatically detect the Linux (any distro) install so you would have to add this manually. I dont know anything about the Windows bootloader myself. A better way is to use your Linux install CD/DVD to repair Grub in the MBR. This is a very easy step and 99% of the time it will automatically detect Windows so you dont even have to manually add it.
32 vs 64 bit? Oh boy! This is one big can of worms in here! Just do a search, there are two-three very good, very long threads on this issue. I went 64 bit on F8 for the first time and I can honestly say it was no harder than 32 bit. Flash is no longer a problem and there is nothing "extra" to be done. One down side is you will most likely have 32 and 64 bit libraries for many apps. Some, like Wine, you need both. Others just installs both. The more apps you have the worse it gets. Some people strip out all the 32 bit packages, this is certainly an option. Personally, I saw NO advantage running 64 bit over 32 bit. But I dont do any data intensive work either. I wont argue this point, this is MY experience. I continue to run 64 bit on my big desktop rig. I run 32 bit on everything else though.
Ubuntu vs Fedora? Again, do a search, you will find more material then you want! It is a main topic. Many of us like Ubuntu, it is a good distro, it is just different. Which is better? No sir, I aint going there! I actually prefer debian to Ubuntu, but Linux Mint and PCLOS are also very good distros.
If I were you, and since I like Fedora, I would repartition so that I had an adequate (but not much larger than the OS requires) Windows partition, An adequate Linux partition, a 2GB swap and the rest as an NTFS data partition to be shared between Windows and Linux. Adequate would be, at most, 20GB for each OS, this is even generous. All personal data would go in the shared NTFS partition. Linux can read/write to this with no problems with the default installed NTFS-3G. Then, when it comes time to update Fedora every six months it is a breeze. It takes me a few hours to fully install and tweak the OS.
Should you stay with Fedora? Only you can answer this. Linux is basically Linux, once you figure out the basics you will use any distro with ease. But I personally think Fedora is just better than the rest. By all rights debian etch is the "perfect" Linux distro, but I just like Fedora. So I can understand where you are coming from. It is always good to expand your horizons, but i consider Fedora home.