Stucco install options

I have a frame house with fin aluminum windows. The stucco around the windows is 3/4" thick around the window perimeter and is flush with the face of the window. The stucco recesses into all four sides of the frame about a half inch. The interior is 1/2 sheet rock butting the window. The existing frame is two inches wide.
How do I measure for vinyl replacements?
How do I remove the old window?
What will finish the joint between the stucco and the new window?
Can anyone help please

This is not a standard installation for a do it yourself job. Find a professional in your area that is familiar with aluminum removals in Stucco. You don't want to buy a high performance window and have an inadequate installation. I,m sure that there are homes in your area that have already been done. Perhaps you can get a referal from one of those.

Take a diamond blade cut a kerf around the window, then take a saws all and cut through the nailing fin , pull out the old , install the new, finish to taste.