I am looking into a car with a thin head gasket installed in it.

I was wondering apart from raising the compression, how does it affect the car? Like I researched on OH and found out that Adrian from toda said it'd retard the timing.

It has adjustable cam gears (running on stock ITR cams), does it have to be set by a tuner, or just by a mechanic?

And in other places that it says that the valves might hit the pistons because of the head gasket.

It's running on stock ecu, wouldn't the higher compression and different cam settings etc make the ecu confused. So would I need an ecu like hondata?

I'm noob to engine internals, what do I do here?