The ideas you described don't help much because they aren't very deep. It goes without saying that you want to develop your pieces.
In the italian you have a few possible ideas/plans:
You can play for a quick d4 (with or without c3), opening up all of your pieces and gaining space. How this turns out depends largely on lots of tactics but in each case white will be primarily hoping to grab the initiative, even if he loses material. Last time I checked most of the tactics from a quick d4 lead to equality with accurate play for both sides.
The slower plans, when d3 is played, are not as easy to grasp because although you have developed a few pieces for one thing with little pressure on the center black can do the same, and you still don't have as many open lines for attack as you would like. In the italian these subtle lines usually begin with 4 c3 Nf6 5 d3, when white can try a few things: gain space on the queenside with b4 and a4, though it's not clear how necessary/effective this is and it does weaken things there in the long term. He can play for d4 as I mentioned earlier but after much preparation. He can also play for f4. Black has similar ideas since his position is fairly similar. Because the game is closed there is a lot of slow maneouvering while executing these plans.
This is probably why you're confused after the first few moves (well when I used to play this stuff religiously I was at least): because after you develop a few pieces you see that (well if you play with d3 anyway) because of the closed, and quite symetrical position, making progress for either side is not so simple. The ideas of the italian game, and any opening for that matter, go way beyond just simple development and don't be surprised if they aren't so easy to grasp at first.
I've heard many times that one should learn the ideas of the openings, not just memorize the moves. I struggle with this, though... Could someone break down the ideas of a basic opening, for example, the Italian game? It's my understanding that 1.e4 strikes in the center & opens the gates for the B and Q. e5 does the same. 2. Nf3 attacks the e5 pawn, developing a piece and adding to central control. ...Nc6 protects the pawn and develops a piece. 3. Bc4 takes aim at the weak f7 square and develops a piece. This is all logical, but doesn't help my plan in most cases. I understand the notion that targets in the game (backward pawn, hanging piece) are dynamic and constantly changing -- but what is the purpose of the opening's idea if it doesn't help guide you into a playable plan?