Are the restrictions for a work permit lesser if you have a child in thailand? (not married to his mother)

As far as I understand you have a lower minimum salary requirements.

But more important. Does the company need lesser requirements if it employs a foreigner with a thai spouse? lesser capital, lesser thai employees?!

No, does not change at all.

The lower salary only would come into play if you have an extension of stay based upon being the parent of a Thai which would be the income requirement of 40k baht unless you used 400k baht int the bank option (no minimum salary of any amount). If you had a multiple entry non-o visa there would also be no minimum salary either.

If you did the extension based upon work the minimum salary would not change.

For the work permit dependent upon where you apply for the work permit the registered capital could be lowered to 1 million baht and Thai employees to 2.

For the work permit dependent upon where you apply for the work permit the registered capital could be lowered to 1 million baht and Thai employees to 2.

So with a thai child I could get a WP from a company with 1 mio baht capital and 2 employees? Is this also possible if I would be the 49% shareholder?

As I said it depends upon where you apply. Every work permit office can have a different interpretation of the rules.

The ministerial regulations were changed about 3 years ago and were not made public. I have never seen a translations of them. Under the old rules it was possible.