Order & highlights - How to open the cylinder head in Z12XE

[Aditi]

Good night friends,

Further to the above subject (https://www.corsa-b.co.uk/forum/viewtop ... 54&t=21621)
I would like to know important tips before I open the cylinder head to replace the Worn head gasket, and if its necessary refurbish cylinder head.

Is there some necessary tool that I'll need?
what's the order of closing of cylinder head bolts ? and whether it's better to replace them with new ones, or that it is not necessary above this engine..

Timing chain - how do i open it right?
Is there any Manual guide?

I'd like any help on (from personal experience, or information sources for the proper opening, etc).
Thanks in advance,