I think rome gold is patched to 1.5 yes. don’t uninstall everything until you have tried everything out, as you may not need too.
When you get an error, then when it shows on screen press Prt Scr [print screen], then open your photo editor and go to edit, then paste as new image and you will have an image of the error message, then cut it out and post it. Or write it down in its entirety, it will stay on the screen until you do something.
What I meant was to copy the entire game folder to your documents folder or anywhere not in program files, this is because vista creates a virtual space for program files so they may not show up when you run the mod.
Yes what you have done should be fine.