Lisbon to Evora

We didn't drive in Lisbon, so I can't comment about that. We did go back to the airport to rent our car, which took us right to the highway. We went farther than Evora, I think. We settled for a touristy bus excursion from Lisbon that did Evora with a few other places. You are not wrong to sleep there, however. We particularly enjoyed sleeping in Guimares, at the convent (?) Pousada.

You can easily take the metro from the Rossio metro station to Sete Rios. After you exit the metro, you walk a bit to the train station where you get the train to Evora. You can also take a taxi from your hotel to the Sete Rios train station. It's an easy ride to Evora with lots of cork groves to see on the way.

If you will be going in the next two weeks (as you mention), you can go ahead and purchase your train tickets for a savings.

Renting a car in Evora and driving there is easy but parking is a bit of a challenge but not excessively so. Auto Europe has great service and prices. You can take a taxi from the train station in Evora to your car pickup.

I drove in Portugal for a complete 2 weeks from south to north, east to west and I can't understand why there would be horror stories there.
It is similar to other countries such as France, Spain and calmer than southern italy.

We rented a car for a month starting in Lisboa and had no problems at all ! Folks were so kind to let us move from lane to lane - with blinker on of course- and made room and time for us ! Also, wonderful is that all cars stop for all pedestrians in the crosswalks which is just like here in Vermont. While roads were often one way due to very narrow streets, and we had some problems since there are really no street signs, we managed well with the GPS and Google maps on our phones. We loved Evora and got an airbnb with "david" a few minutes walk from the walled town. It was great !