I am building a torch that contains a 3P2S array of 18650 batteries.

The overall array voltage is 7.4V nominal with a roughly 7Ah capacity. I was wondering how best to charge it, and how best to keep it for the best shalf life?
Other questions:
Do Li-Ion batteries last best on the shelf if left charged or discharged?
How best to ensure that the batteries remain balanced?
Would it need to be disassembled and rebalanced often?