Hey vertex.
I live in Salta (for 5 years now) and run a software company here. Let me know when you are coming and I'll be happy to show you around!
If you like it here and would like to stay for longer term I can also help with rental and/or other details.
As AHansen said, the bus is the cheapest way to get here - even though it's a long trip the buses are comfortable and the difference in price makes up for it.
It doesn't get *that* hot here and people always take a siesta hot or not
Climate here is nice and hot during the day and cools down at night (right now it's cool during the day as well, but sunny most days).
But remember that Salta (district population ~500k) is a very small city compared to BA (district population ~13 million), hence less night-life, less cultural events, less ex pats, less restaurants and food options etc.. On the upside there's a lot less crime, less pollution and people here are more open, friendlier and live a more relaxed lifestyle. There are also as people mentioned earlier in this thread a lot of great places nearby for day/weekend trips.
If you (or anyone) has any specific questions about Salta just let me know.