GLOBAL MARKETS-Wall St, dollar fall after private jobs data, oil up

* European shares push higher as Q2 gets under way * U.S. stocks, U.S. dollar dips after weak private sector job data * Oil rallies as talks on Iran continue By Sinead Carew NEW YORK, April 1 (Reuters) - U.S. stocks fell for a second day and the dollar dipped after a weaker-than-expected report on private sector employment spurred investor concerns that a highly anticipated monthly U.S. jobs report on Friday could also point to slowing economic growth. However, oil futures r