Variable power supply

[tensatsukai]

G'day,

 I need a DC-DC power regulator with a variable output.... or something along those lines

power source is 2x 18650 3.7V 3300mah batteries connected in series
DC output voltage needs to be variable from 3.7 to 6v
it needs to be user adjustable preferably via buttons and have a display showing the current Vout and battery life remaining as a % Preferably
a master power button to turn the unit on and allow adjustment (but no power to output) and a momentary NO switch to activate the power output
and a USB power inlet to charge the battery ( if possible unit can be used whilst charging)

Thanks for any assistance