Does electrical wires on exterior need to be in conduit

The IRC or the NEC doesn't apply here, common sense does. What you need to do is apply a paintable silicone acrylic or silicone caulk to the back of the box and around the entry hole before you screw the box to the wall. There should be holes inside the box or external ears for mounting. The idea is to stop water from going behind the box and around the conduit into the wall. Don't be afraid to use it, you can wipe off the excess with a damp cloth. Good luck.

1. It is okay to drill from below as long as you know, for a fact that you are not going to hit ANYTHING, otherwise go into the attic.
2. The conduit can run on the floor of the attic but I would use a two hole strap and get it above the insulation .
3. I would use a plastic pull box with a plastic cover, the backless may not give you the support that you need when pulling your wires.
4. As for the holes that you make, I would use a fire foam to seal.

Update to the post and for your reading pleasure. This is for Carlon

The following is from here. It was going to be hard to copy it on my scanner so I copied and pasted the BEST part.

Approved Uses: Typical Applications:

• Concrete slab – NEC Article 362
• Walls - wood stud, masonry and metal stud – NEC Article 362.
• Ceilings - permanent or dropped (free air only) – NEC Article 362.
• Exposed – NEC Article 362
• Public Assembly – NEC Section 518.4, in nonfire rated and certain five rated structures
• Prewired – NEC Article 362
• Classified by UL 1479 for Through Penetration Firestop Systems in UL Guide Category XHEZ and current UL Fire Resistance Directory
• Three hour rated floor/ceiling assemble
• Raised Floors – NEC Section 645.5(D)(2)

• Exposed or concealed in building above three floors when a fire sprinkler system is installed in accordance with NFPA 13–NEC Section 362.10(2)

  For use in residential attics up to 3 feet above the bottom of the ceiling joist.

Update to the Update. Before anyone says anything I realize I made a mistake and I am falling on my own sword. The above is for Carlon Flex-Plus Blue not Carlon Resi-gard (Think it is time to go back to the eye doctor) so here is what I did find.(I was sure the OP said flex plus)

The PDF did said attic but going in to not through but it did also said that "Resi-Gard is rated as a general-purpose raceway per National Electrical Code (NEC) Article 770, for Optical Fiber Cables and Raceways and Article 800 for Communications Circuits".

So with that, I would use Resi-Gard in the walls and Flex-Plus Blue for your raceway in the attic.