Driving 3 x 3W LEDs with just a USB battery pack on an Arduino Nano?

Hey folks...

Here's the deal:

I'm currently working on a project to use a 5V Arduino Nano V3.0 to control a trio of dimmable 3W (I think they're 3.x V/1A for max. brightness) and powering the entire setup using an Anker PowerCore+ Mini (output 5V@1A).

I want to make sure my assumptions are correct before I proceed too much further.

1a) When powering the Nano using the on-board USB-B port, the maximum current provided by the 5V output pin is ~500mA.

1b) It should be possible to use a USB cable to just supply the full 5V/1A from the battery pack to the VIN output. Then if I decided to split off a parallel supply for the LEDs and divide the current in half, I'd have 5V/500mA available for both the board and LEDs. Advantage of this method over 1a is dubious at the moment?

  1. Using the 5V output pin and spreading it across 3 LEDs in parallel would result in each LED getting a 5V/~150mA current at most.

  2. Ideally I'd have to attach something like a Buck-Boost to the 5V output pin's initial output to 12V, and then combine the paralleled 12V/150mA supply with some sort of circuit like an Op-Amp to change it from 12V/150mA to ~3.5V/1000mA

If the above assumptions are correct would any of y'all have recommendations on what circuits to use at each stage?

If not, what am I getting wrong here?