I would definitely take Neymar over Lavezzi but I am one of them people who always builds a team based around youngish players. Neymar for 15M is great, he's versatile, can compete almost straight away, becomes a mega expensive player and in my game at the start of 2012 Neymar would still cost me 30M according to the scout reports, once he is bought that will double for years so I would take Neymar.
As for the right backs it all depends on the budget and how much you would want to pay. Players like Philipp Lahm, Sergio Ramos will cost you up-wards to 30M but would be able to come straight into the team, Srna is 29 but on my game he was in his last year of his contract and would be worth purchasing if you like experienced with good freekicks and crossing. Or you could go for Gregory Van Der Wiel who can speak English already or Rafinha, both shouldn't be too expensive.
Be greedy and buy a ST and a RB with Manchester City it's easily possible