Which cable/conduit should I use to run a new 240 volt line for an oven?
Of the options you are considering, I'd think option 2 makes more sense, and 4-5 feet of conduit - in most cases the conduit will just be continuous from the junction box right through the wall, no particular fuss "as it enters the house" - Come down the wall, put on an LB, drill a hole in the wall, insert conduit, connect to junction box, connect to LB; done. This might be aided by drilling at least a pilot hole from the inside out to make lining it all up easier. Also pick up some duct seal (gray putty, in the electrical aisle) to pack the wires as they leave the LB.

If the wires are entering via an existing conduit, you just need to connect a new conduit to the box that conduit terminates in, and your junction box.

EMT or PVC is six on the one hand, half a dozen the other. I use metal aboveground and PVC below, mostly.