>>>1) why do we pour water from becher into wine bottle before kiddush?
I’ve never see anyone do so
>>>2) it says if you’re sandek for 4th or 5th generation (which one?) you go straight to gan eden, mekor?
Probably the same place that is says if you have seven sons you go straight to Gan Eden. Along with various other straight to Gan Eden methods. To be sandek for four generations you would need major arichus yomim.