Hey jetaway, jer again.
Glad you enjoyed my little travel tale
The busses and trains should run on weekends but may be fewer than during the week.
Although there is very little info to be found online about the Portuguese side of Villa Real de San Antonio, you can get all you need on Ayamonte at
www.ayamonte.net
If you click the button "Informaci�n", you get loads of useful telephone numbers for the city including the "Oficina de Turismo" ("Tourist Office") which is (95) 947 0988.
Not sure how much English they will speak there.
Another website on Ayamonte at
www.geocities.com/Colosseum/4411/aya/plano.htm shows some useful photos of the city and the Guadiana river with the bridge ("Puente Internacional" or "International Bridge") that I mentioned just north of the city. You can see how narrow the river is and how close Ayamonte is to Portugal. Special attention to "Plano 3" ("Map 3") which shows us Ayamonte and Villa Real de San Antonio loud and clear
By the way, on "Plano 1", point "2.PUERTO Y MUELLE PESQUERO" ("PORT AND FISHING DOCK") is where you can (or used to be able to) get the little boat to Villa Real de San Antonio. You may want to ask at the tourist office via phone or e-mail before you go if it still runs, it was a fun way to cross the river (beats swimming in December anyway

)
Maybe I judged Ayamonte wrongly, it may be nice from what I can see online now but years ago I got a bad feeling there even though I was only there for an hour or so. I may have jumped to conclusions due to the slimy "taxi drivers" that were all over us offering us rides to Portugal via the bridge.
Saludos,
jer...