BMW 6cyl. Head Gasket Replacement Sequence Tech Advice Needed

[WorldA]

Hi there BMW forum,
I am a long time VW mechanic mostly messing with the old diesel and gas vw's and have done a million head gaskets on VW's. I have a customer now who has a BMW M3 strait 6 .The vehicle is boiling over and overheating giving me all the signs of a blown head gasket. We replaced the thermostat and all thats left is for me to use a pressure tester on the cooling system for me to know for sure this thing is about to get its head removed.
Is there anything else that could make the car boil out coolant like a head gasket issue? The coolant is circulating from what I can tell because the heater is blowing full hot air when it warms up. The car also sat for 6 months in a garage with a bad starter which I replaced which was no fun.
How can I properly bleed out the air on these strait 6 BMW motors, and do you ever see air pockets boil all the coolant out? The coolant was also leaking past the cap and down the motor onto the ground, fyi.
So the main question here assuming that the head is bad, Is there any special tools I need to pull and replace the head , like cam lock or timing belt tentioner tool? Is there a inspection hole on the trans where there is a timing mark for TDC? Is there a proper way to mark the timing chain ? Im not used to the BMW design , but I have done normal repairs on these. Is there a spitter hole where I can see the coolant circulating?
Just any basic advice would be greatly appriciated, I am not doing this job for a few weeks so I am preparing myself in any way I can.

[marti5]

This may be of use:

Replacing cylinder head gasket in bmw m3 | Wonder How To