I'm pretty sure you'll get a great collection in no time - the only thing I struggle with here is the summer heath, but all the temperate-warm plants grow pretty well - I see your spider fern is pretty nice too
Don't know if you already know it, but in case, Acao, the catalan orchid association, has a cute expo/selling once a year (this year was in June)
Ola! I am not in Barcelona, originally born in Madrid though, but I live in a place in the USA, with a lot of summer heat as well. Shade, good drainage and daily watering when the temps get 85 (F) and up approx. I reccommend Phrags and Paphs. Since they must remain wet all the time, there are no issues with heat or dessication. You just dump more water in there.