On my Hwei ability, can I draw a Porobot and float 2 energy before discarding a Porobot to get two free energy?

Yes — with the right timing. You can't interrupt Hwei's ability mid-resolution, but you can float before it resolves.

Here's the line that works:

1. Hwei moves → his "When I move" trigger goes on the Chain (Closed State) and you have priority.
2. In response to the trigger, exhaust 2 ready runes to float 2 energy (runes can be exhausted whenever you have priority — FAQ #2353).
3. Hwei's ability then resolves as one uninterrupted effect: draw 1, discard 1 (you pick the Porobot you just drew — Rule 422.1.a), and since Patched Porobot is a Gear, you ready up to 2 runes — including the ones you just exhausted.

Net result: 2 floating energy and those runes ready again. What you can't do is draw the Porobot, exhaust runes, then discard mid-resolution — once Hwei's effect starts resolving it completes in full (Rules 340.1, 401.2); you'd only be able to add resources mid-resolution if the effect made you pay a cost (Rule 357.1.a), which it doesn't.

One correction: the energy isn't conjured out of thin air — you're exhausting your own runes and Hwei refunds their readiness. Your pool keeps the 2 energy until end of turn (or the draw phase if this happens early), so spend it before then. Also note Porobot is Unit and Gear, so it also satisfies the Unit branch (+3 Shield) under the natural reading of the type check.