Hi, I'm Italian so, sorry for my bad English. I have to buy an Arduino, but I heard about Arduino UNO R3 and Arduino Mega. If I'm not wrong, Mega has more pins than UNO. I have to build a small project: I want to use this http://www.ladyada.net/products/tfttouchbreakout/ screen, this microsd card reader http://www.robot-italy.com/it/microsd-shield.html, this printer https://www.adafruit.com/products/600, 12 buttons (or more... I'll see), and, if I find something else, I'd like to add it to the project (maybe some sensors). Oh, I forgot: I want to use an rgb led too. I've never used Arduino, but I want to buy an Arduino for either learning and this project. When I finished to use it for learning purposes, I want to build a very very small computer and I don't want to buy an Arduino uno discovering later that it hasn't got enough pins for my project.
My question is: is an Arduino uno equal to arduino mega except for the number of digital/analogic pins? If I buy an arduino uno, is there a simple mode to extend the number of pins or it is better to buy an arduino mega?
Another question: I read some tutorials that use the same pin for an Led (13). Is it compulsory to use the pin number that it says in the tutorial or can I change it (not the type -digital/analogic-, only the number). if I would connect the led in pin... 10, what it would happen?
Thanks a lot for your patience and for your answers...
Bye and have a good weekend!!!