Q's about TUNING and did i blow up my head gasket?

Yeeeaaah - it feels great when I hammer the pedal to the metal, the boost preasure rises to 12 psi and my rear tyres is skidding a little due to shear acceleration and leaves a mark from my Goodyear Eagle 225*50 16 GS-D+ - But I think it has a price to boost a L28ET S130 engine so much without any other alterations than a manual boost controller and a home made 76.1mm stainless exhaust pipe.
I have been fault seeking on my engine for quite a while and i found some minor and some major errors on it. The max preasure has been 12 psi from the day i purchased the car a year ago, but the car did'nt run very smooth when i was driving nice and quietly down the road, but when i floored it it felt OK.
The following errors was encountered:

1. Faulty ignition vac. advance....($140) in denmark!!!
2. Ignition timing 9 degrees to retard.
3. Leaking Vacum Crontrol Valve on the intake resulting in high idle....($96).

THE TIMING MARK ON THE FLYWHEEL IS 21 DEGREES OUT OF ALLIGNMENT WITH TDC!!!.

After setting my timing (a month struggle finding the error) I took the car for a test drive with boost set to normal 6.8 psi and the car was running smoothly and silently down the road - quick response even below 2000 rpm which i never had tried before and generaly felt like you could expect from a 200 bhp car.

After the first runs with low boost i raised preasure to 12 psi and listened very carefully under acceleration if there was any indikation of detonation - I could'nt hear any so I found a good highwayand tried to floor it i 5th gear pulling the car to a speedometer indication of 145mph and holdig it there for app 2 miles. When i got home i checked the engine compartment and found it soaked in water coming from the coolant water expansion container - and there was 2 liter of water missing in the radiator.
MY QUESTION IS DID I BLOW UP MY CYLINDERHEADGASKET OR COULD IT BE SOMETHING ELSE??
I naturally reduced boost preasure after that insident and the car runs fine but of course without the same amount of power. There is no water in the oil and it seems that there is no oil in the water. the car did'nt overheat at any point during the run and it was of course up to normal operating temperature.

If the gasket is blown which gasket should i purchase and from where???

When i have the head of should i then mill of the cylinderhead to raise compresion like the Stealth, or should i leave it as it is???

What is O-ringing the block to hold the gasket in place under detonation and how is it performed???

When I am at it I think that I will port match my manifold with the cylinderhead. Is there somthing that I should be cautious about in that operation???

Will i benefit from a Webber big throat trottle body without changing the Airflow meter - where to get one and how much $$???

What are the requirements to my EFI system after these mods and how can i perform them - both cheap and more expensive methods can be considered pleaase ad a price if you have any??

I will ad a intercooler in the same operation so i would like to know wich one is the best and where to get it??

A lot of Q's from a Dane with NEED for speed - I would like to win a competition called the fastest car i denmark, where you should perform 1000m run like a drag racing but about 4.5 times as long followed by a slalom run.

Hope to get many answers to my Q's

Thanks Brian Madsen

PS by the way the car is a 280 ZX TT 2+2 from 83