Skipping?

If I get a runer to say, Yak's, can I skip all the proph missions up until my character would normally get there?

Proph is the only campaign where you can skip like 90% of the missions and still complete the game. It's been a long time for me, but I think the only missions you need to do are sanctum cay, the crystal desert missions, and a few others. Some other dude might be able to give you more complete info.

Walk from Dorknars to Iron Mines of Moladune and do the remaining missions...

To answer Arzock question yes you can skip all the missions that would normally take your character there.
To clarify more on Flex's post you can skip pretty much all the missions in prophecies if you can get a runner to get you to thunderheadkeep which then takes you to the ring of fire misssions therefore making it only 4 missions before you finish the campaign.

You actually only have to do 4 missions in Prophesies. You can get a run to Beacon's, then a run to Droks. From there you can get a run to THK. You must do THK and the three missions on Fire Island to complete the game. You'll be at the end, low level and completely useless.

The most common bits to miss are everything between LA and Sanctum Cay. If you want to ascend in Proph, you must complete Sanctum Cay and the three desert missions.

If this is your first time thorugh Prophesies, I'd highly recommend not skipping anything. The missions are fun to do.

Yes you can skip them, but you will probably not be where you should be lvl-wise and you will miss out on a big chunk of the storyline.