can HK Viosa dor german Visitor be renewed by a trip to macao?

I think what you mean is that your validy visa-free period in HK is about to be out, so you plan to exit Hk and go to Macay for a period of time, and then return to Hk for some time more. Personally, it will work, but you'd better not repeat this again and again. Do not overdo a thing, play it just right.

Yes, no problem according to people I have spoken to. The easiest way is to take a ferry.