In a nutshell we need width, pace, and creativity on the ball. That means quality attacking fullbacks (who can also defend), top class wingers and a top class creative second striker. So, five players if we have the funds for an overhaul. If not, then we need to get in at least 1 quality fullback, 1 quality winger (preferably on the opposite flank) and the creative 2nd striker.
Beyond the five mentioned, we also need to add another quality striker as 3rd choice, another class centreback to understudy for Carragher (even if Skrtel proves to be quality) and another back-up keeper to replace Itandje (I like the veteran Premiership keeper idea, Mick).
On the issue of funds, I think much will depend on who is manager. If Rafa is still in charge, I suspect he will be told to make do pretty much with what he's got or to sell before he buys. If a new manager comes in, he will be given the money to splash out on transfers--all new managers get a war chest because most wouldn't take the job otherwise!