Federal officials trying to contain the multibillion-dollar cost of the savings and loan bail-out are mobilizing more than 1,200 regulators to take control of all remaining insolvent S&Ls over the next few weeks. The massive government takeover was announced Tuesday as financial regulators scrambled to implement the first portions of President Bush's S&L overhaul package. Meanwhile, the Bush proposals were receiving favorable reactions from Congress although some lawmakers said they had reservations about some aspects of the proposals, in particular the $40 billion estimated cost to taxpayers. Officials of the Federal Savings and Loan Insurance Corp., which insures deposits at S&Ls, and the Federal Deposit Insurance Corp., which performs the same function at banks, predicted that within a month they would have joint regulatory teams in place at some 224 insolvent S&Ls.