TalkChess.com

1) How do you get a best first move near the leaves of the search tree ?

Best move from IID or hash are probably not the best moves at these low tree heights and there probably will not be a capture winning material

1a) If there is no best first move near the leaves of the search tree can you still use PVS at these lower tree heights for you get many researches which only cost extra search time ?

I think usually people use PVS only for depth > 2, because otherwise indeed the chances to pick the best move first are not large enough, and you would just do many needles re-searches. You would have to experiment. It is at these depths just above QS that the static move ordering is most important. At larger depth you can usually rely on the hash move, or IID.

What I found helpful is let the engine print positions where it achieved a cutoff only after searching many moves. By looking at those, you might get inspiration for how the engine could have seen in advance that move would be the proper move to play, and could have sorted it earlier.