Hi, Mark
Specifically for that location, I only went through once, so the rest is "general".

Yes, long lenses are suitable for some landscape photography. They're good for isolating scene
detail that you can't always easily get to, AND... to give a scene a particular perspective that a
closer position would not yield.

In various trips, the latest major one being about 2016, I took along my 50-500mm. I cannot
locate any pics from then in a short time, but I took shots using it in Central Oz, at Watarrka
NP (Kings Canyon) and around Kata Tjuta (The Olgas). I used it less around Uluru, but again
along the roads.

Your bonus Q is a bit hard to answer. For shorter FL primes I'd say Sigma Art lenses. I'm sure
Tamron would have equivalents, but I'm not up on them. But it sounds you'd want longer than
most of Sigma's Art lens lineup (max 135mm prime, or 50-100 zoom for Canon).

What FL or zoom range are you looking for? Certainly, the Canon L lenses are dearer than many
other brand FL equivalents.