1-Forget about the Tarjeta Dorada discount. The Promo fares are better to book in advance, as the have greater discount (70% vs 40%) than Tarjeta Dorada for AVE trains.
If you want to take the advantage of Tarjeta Dorada, you will have to use it only on MD trains and Avant services, as these trains have no promo fares. The Avant trains might be quite busy, but the MD trains aren't very busy at all, and they are a super nice journey. In any case, if you think that the train might be sold out, you can always buy a Tarjeta Dorada at the train station and then prebook online using the Tarjeta Dorada number at www.renfe.com
2-The best way to book online is at www.renfe.com . The website isn't quite bad, just remember that Todas means all stations in a city, and the stops you want is Málaga María Zambrano for the AVE, Avant and MD trains, Córdoba Central for the AVE, Avant and MD trains, Sevilla Santa Justa for the AVE, Avant and MD trains, although if you use MD train from Málaga to Sevilla or Sevilla to Córdoba they also call at Sevilla-San Bernardo, which is a station that has simple connections with the Tram and the Metro Sevilla to go to the city centre (the station is very close). Sometimes the system doesn't like US cards, but that is because the cards must have set up the Verified by Visa or Mastercard SecureCode safety systems that are widely use in Europe online commerce. If it stills doesn't work, create or use a PayPal account, then use the PayPal option to pay at www.renfe.com
3-There is a Cercanías train (commuter train), C-1 line, that links Málaga María Zambrano station with Málaga Aeropuerto. The train is frequent, have a look on Cercanías Málaga renfe website section. This train is free of charge with your AVE ticket (when you buy your ticket at renfe.com it will have a code called Combinado Cercanías, this entitles you to use Cercanías trains in Madrid, to go to the departure station of your AVE train, Puerta de Atocha, and then to use the Cercanías trains in Málaga, wherever you like within Cercanías Málaga network, including Málaga Aeropuerto, up to 3 hours after you arrive with your AVE train). All of this free of charge. You exchange the code for a free commuter train ticket at the respective Cercanías ticket machines. (touch Combinado Cercanías, scan barcode or type the code, then the commuter train ticket gets printed in few seconds)
4-Renfe company sometimes logs the trains onto their system whenever they like, so the 60 day rule is not exact. So everyone keeps checking the website every day until the train is loged. If the train doesn't appear, then wait for tomorrow. If it appears, buy then, as Promo fares are limited and they can be sold out quite fast.
5-Málaga has a Metro (it's more a tram, but they call it Metro). Have a look at their website: https://metromalaga.es/
If you use public transport in Andalucía, buy a Consorcio Card. It can be topped up with credit, and it is valid to board buses, trams and Metros in all Andalucía region, and it can be used to pay for a Renfe MD train ticket at the automatic machines (like a credit card)
6-Tolls in Spain: Manual means notes, coins and credit card. Automático means only credit cards (sometimes is just take the ticket at the start of the toll road, then when you exit, insert ticket and pay). If you want, you can ask the rental car company for a Via-T device, that pays automatically the tolls without stopping.
Few things about Via-T: If you don't have a Via-T in your card, do not enter the roundel blue T lane in a Toll, as that lane is only for those who have a Via-T device (to go faster). If the sign is a squared blue T, that means that you can use Via-T device, but you can also use another payment methods.
