PVC vs. Metal vs cable vs conductor

Greetings all, I'm back with another question for the pros on the deck area I'm working on.

Okay so I plan to add three receptacles to the side of the house (which is brick) to provide some receptacles to the covered portion of the deck. So I have some questions here and a diagram of my intended battle plan.

1. Is my plan below legit? Can I tap into the back of an existing box inside the house to bring my power outside? If so, can I bring it right into an outdoor box or do I have to bring it into an LB first and then go from the LB to a receptacle box 4 or 5 inches down from it?

2. Conduit. Should I use PVC for this or rigid metal? Does PVC look considerably crappier than metal? Are both "paint-able" since i think the lady of the house is not going to want bright silver or dull grey right there.

3. Wire/cable. Should i use THHN/THWN or UF? If I go PVC can UF be run inside PVC conduit?

4. Conduit Fill. What size PVC or metal conduit would I need to use for a single 12/2 UF wire or 3 #12 THHN/THWN wires?

Thanks in advance!

ANy of the receptacles outside must be GFCI protected. Now, you could put one at the beginning of that chain and protect those further down the chain by using the load terminals to feed them. So, from a technical standpoint, it can be done. Now, whether it is wise or to code, I'm not sure.

Not out the back but out one of the holes provided for a cable would be fine.

Use either raceway you desire and from the first box to the others make sure the conductors has a “W” such as THHN/THWN conductors. UF could be pulled in either but it is harder to installed and not needed.
If you choose EMT make sure to use the correct fittings and bond the metal boxes. PVC will not hold paint as good as one of the metal raceways.

As has been pointed out protect all devices with GFCI.

Don't forget the weatherproof-in-use covers.

Just to reiterate, I'm pretty sure 1/2" is plenty for 3 12 gauge conductors...?