1. The vast majority of anglers today would start with a Weightless Senko either T-Rigged or Wacky Rigged. T-Rigged in cover and wacky rigged in more open water .... There is always exceptions to the Rule.
As it quivers, a Senko falls slowly through the water column .... always watch your line for movement not caused by your bait or you. Not sure, set the hook it's free.
If this is not working, add weight so that you can keep the Senko in contact with the bottom as you retrieve it.
2. There is probably no need unless the cover (branches etc.) force you to keep the weight close.
I hope this helps.