While fluency in the language is not a must (roadsigns are pretty much the same all over the Western hemisphere, and it's not that you really interact with people in petrol stations), I agree with Gaucho that some adequate knowledge of Spanish could be useful should you have any problems en route. Bear in mind that from Salta to Mendoza you'll go through many desert-like areas without any mobile phone coverage whatsoever, especially when crossing Catamarca, La Rioja and San Juan (roads in La Rioja rank among the worst in Argentina).

Even though things will definitely change over the following weeks, as far as I know Córdoba city and San Miguel de Tucumán were not affected by floods. Some areas of both provinces have been, but things are getting better, especially in Córdoba. In Tucumán they still have problems in the southern part of the province. If you're going from Córdoba to Salta straight through RN9/RN34 you should be fine. If you take the detour via Tafí del Valle (Tuc.) then the road from Acheral to Tafí has been closed for a few days now (RP307), police are diverting traffic to RP324 (also known as "Ruta Interpueblos"). Once again this may change over the next days/weeks.

Last but not least, for some awkward reason Google Maps has been showing for years that RN7 (Buenos Aires - Mendoza) is closed near Vicuña Mackenna. That road was indeed closed - 10 years ago!