New to this forum and very uninformed about mobile and internet in Europe. Using an IPhone which I am comfortable with and have used extensively in Mexico (via WIFI, Skype, etc). I purchased a YOIGO sim card on ebay to insert into an IPhone which will not accept it. No credit on the card so I need a lot of help when I get to Spain and actually try to use it. We will be in Barcelona for 2 nights, then Costa del Sol for 8 nights. I was told that YOIGO charge for internet use is flat 1.20 euros/day. My specific questions:
1. Is the 1.20 euro daily charge for unlimited data usage?
2. Where should I go to activate the card and what will I ask for (what am I trying to buy)? I am thinking maybe I buy 20 euros of credit for example and then each day that I use it, the fee is deducted from that credit?
3. Are there settings that I will need to change or other changes to make on my phone to make it functional?
4. Although purchased primarily for internet usage (and therefore Skype via the internet), are the options for a few calls in Spain and for calling back to the US better or just as good as using Skype?

As you can tell, I am pretty clueless about all of this so would be so appreciate for any knowledge someone is able to share! Thank you!