1. Not that I know of, maybe some obsure mob in Japan do but its unlikely, and finding them and affording the unit they sell will be the first 2 miracles towards your sainthood !!
2. As I understand it the 4E-FTE in at least the EP90 Starlet has two buttons on the dash for (something like) low (5 psi) and high (9 psi) boost.
3. This I don't know but looking at most other Toyota turbo's, going past 11-12 psi regularly in an otherwise unmodified engine means that you are likely to experience bang, smoke, oh bugger sooner rather than later.
4. Can't help here either, Google should become your new best friend.
Cheers,
Mitch.