djozz
(djozz)
5
Welcome to BLF hyperduc.
That is a well-done build of a very useful flashlight. As said above, nothing wrong with your soldering skills 
As for your question 3) , the voltage that the emitter sees is not the same as what the power supply provides. There are resistances in the circuitry that cause voltage loss, in your case some voltage is lost in the leads from power supply to driver, in the driver-spring and the ledwires, but also about 0.2V in the 7135 chips.