Possibly outdated info
Hi, I had to turn in a different route (modular without instructing stateside) but my research with other posts, legal texts and direct contact with the few F1-schools on a field trip up and down the Florida coasts revealed the following:
You can do the PPL on an M1 which will lengthen your OPT by very few weeks if you subsequently apply for an F1 visa, however: I am not sure it is worth the hassle of a double application process, even it is with the same schoo; and especially in your situation (i.e. with your plan). You can change to a different school for OPT once you have acquired your CPL/CFI, which not all schools will tell you; but other than your residential savings I am not sure that's necessarily the greatest idea; PTS may be all the same all over FAA country, but there will be some bureaucracy involved with a certain waiting period (I was told several weeks, usually), you won't know the local air work area, controllers, satellite airfields, examiners etc. Plus, if you are a good, reliable teacher who cares about his students, there probably will be more apt, more focused students at the school you graduate yourself at.
I intended to go stateside (Ari Ben, that is, with PEA a close second - the others were either not to my liking or financially off the chart) with plenty of glider experience since their syllabus is a mix of 141 and 61, so you might with good preparation on ground school and glider flying save both time and hours in order to get to instruction quite quickly, since those hours are apparently (last checked: Dec 2010) not seen as PPL/ power experience by the visa authorities. However, according to the FAR (and their back-then chief CFI) you can use up to 130 - 150 of them (the last being in theory, the first being more realistic since you still need to get the minimum in PPL, IR and ME training in) it is legal and legitimate.
Not sure how many local instructors stay these days with the 1500 hr threshold, but back then consensus amongst schools and students was that the motivated, foreign, "caring about their students" instructors who were open minded were pretty active in getting hours, which had been one of my biggest concerns along with a transfer request that you mentioned in your post.
Good luck! I am not sure you shall save that much on housing if you find less flight students who are passionate about aviation and booking 2 - 3 lessons a day outside of F1 schools.... just my 2 cents :-)