Soon to leave for my first trip to Spain. Will be in Madrid, Barcelona and Seville. Any special things to know about dressing appropriatly (being respectful, blending in with the locals - not being an obvious tourist)? Any major climate differences between Barcelona and Seville in late February?

I am sorry to admit that I speak no Spanish other than please, thank you and 1,2,3,4,5. What phrases of courtesy should I make a point to learn NOW so as not to embarrass myself more than necessary? I have travelled in Europe and Asia for years but have never felt as insecure about my language skills as for this trip.

Recently on NPR there was an interview with a respected "foodie" who was lauding the quality of Spain's XP (Xavier Pedro I think) olive oil. Any suggestions on where to buy and a fair price I can expect to pay?