for #3, you can not upgrade from 32 bit to 64 bit. You have to do a clean install. I would encourage doing a separate clean install if you wanted to check out 64 bit's advantages and disadvantages(none?). I believe the biggest benefit is the additional RAM it can address and browsing is also supposed to be significantly faster.
for #4, you need to edit your Grub menu. I believe the easiest way to do this is to edit it with root privileges via:
Carefully navigate to the end of the file and you can see all of the menu options that you would see on boot up. Simply change the order of the entries and you will have changed the order they appear on your computer when it boots.
sudo gedit /boot/grub/menu.lst
Glad to be of service, and i hope your other problems are addressed. (I had the Kubuntu problem after installing Kubuntu as an alternative to Gnome, perhaps you installed a KDE only program, such as Amarok, which may have overwritten your loading screen entry. Either way, I have no idea how to fix that issue)