About US-Cars:
In case the Spanish registering laws are the same like in the rest of the EU, you won't need to change the rear lights, as they have an E-Marking, you would just have to add a rear foglight or follow these instructions to to convert two brake lights into fog lights.
The front lights have to be changed, as the genuine US' don't have an E-Marking.
There might be some other conversions that would have to be made, but all just tiny bits, don't know whether there are any special import regulations in Spain though.
About German cars: About 75% of the German Supras are A/T, so it's damn hard to find a M/T at all. Anyway, don't buy one from Germany, there are only 312 MKIV's left in Germany, and the number is rapidly decreasing
Btw: The Supra you were looking at. Did you have a look at the papers? Is it also an import from Gemany? 27k €isactually a good price for a M/T in mainlandEurope, as they go usually for 30k