HELP: arranging return bus for Fimmvörðuháls day hike

My friend and I plan on doing the 14 mile Fimmvörðuháls in one day. I have done research and the plan is to camp in Skogar the night before, then hike from there to Porsmork, and then take the busses back. This will require taking the first bus from Porsmork to Seljalandsfoss, and then transferring from there to Skogar.

Question: when I go to pre-purchase bus tickets for Porsmork, there appears to be three different Porsmork stops: Basar, Langidalur, and Husadalur. Which one would we be hiking to and getting on the bus at? And is this bus stop clear from the trail?

Here is where you would find the bus schedule for reference: https://www.travelade.com/iceland/stories/how-hike-fimmvorduhals-mountain-pass-just-one-day/

Any other general advice is strongly appreciated, as we want to treat this hike carefully and with utmost safety and preparedness.

Thank you.