I'm unsure how far back to remove the stucco - I would only need to remove an inch or two to remove the old window, but I'm wondering about making the new installation water tight.
Any advice on how much stucco to remove, and the best procedure for water tightness appreciated!
Oh, I'm in California so not much rain and no snow/ice if that matters.
Thanks
ken

It would be safe for you to remove the stucco up to about three to four inches around the stucco. You can either use a saw for a clean line or just use a hammer. The one thing you want to be careful of is tearing into the paper begind your lath when doing this, try your best to avaoid doing so. Tour also idealy going to want your lath to stay in good enough condition to use again when restuccoing. Once the stucco is broken out pull the few furring nails around the window and then pull the lath back so you can remove/install the window(s). If you have pierced the paper while doing your demo you can either slide a new piece behind the exisiting or if there are too many nails to do so just fill/cover holes with a caulk. Once you have your framing exposed (sills, King stud, trimmers and header stapple a six inch moist stop to the framming. 1st run a piece across the face of the sill and run it about 5 inches past each trimmer. Then run your vertical peices from top of header and down the face edge of your trimmers and king stud. Make sure the over lap on top of your bottom piece. Get the window ready for installation by running a liberal bead of caulk acros the header, trimmes and sills. Now put the window in. Once you've deternined the window is plumb and level nail it of using 3/4 inch galvanized roofing nails and then put your final piece of moist stop acrros the header and overlapping the top nailing flange. Pull your lath back into place and nail it tighlty and taught using furring nails. Once this is done you can mask of the window and begin to apply stucco. Always best to take the time of doing three coats, scratch, brown and finisc.... Good luck