There are 4 of us from Texas doing the Barcelona-Venice on July 27th. I got airfare on British Airways for $270.00 each from London to Barcelona. We went ahead and booked thru Cruiseshopping.com. We ended up paying about $2400.00 each for a balcony suite. We also went ahead and bought the ship/airport transfers for $65.00 each even because my hubby is a worry wort. He has never been to Europe but I was just in Venice in Jan. Hope this answers some of your questions.
Forgot to answer your third question- yes you can schedule early fights and they will disembark you according to your flight schedule. I booked our flight for 11 am but found out later we could have flown as early as 7 am.