Advice Wanted (Supercharging)

hey guys, I'm new here, but I've gotten a lot of good advice from this site already while trying to fix a friend's car.
-anyway- I'm building up my Probe (its a 2nd gen with a 2.5, m/t) I know enough about cars to do my own work, but there just isn't that much info out there about what this motor is capable of without blowing up. (that I have seen anyway)

my questions are these:
1. How much boost can I add before I have to start really modifying the fuel system? (I've heard of people putting in like 7psi and just some larger injectors and a better fuel pump but I'd like to run between 10 and 15 psi.)
2. How much abuse can the stock rods handle in reguards to boost? (I have ross pistons already -9.8:1 comp ratio-, and I'm planning to get the crank/rods/pistons balanced)
3. (This may sound dumb -but- ) I have searched high and low for formulas on figuring out the VE of this engine, but everywhere I look just gives me a ballpark, and asks for numbers that I dont have because the motor isn't built yet.

anyway, thanks for any help you can give me!

The safest boost to run on a stock engine would be 5-6 psi. I have a 93 GT with a ZE engine with 10:1.2 ratio. Im running 9 psi of boost with turbo setup.I also have NOS but rarely have to use it. I also have a Walbro 190 fuel pump,and 280 injectors.