To my knowledge, u still get about 90 days after expiration of OPT. And about the tax paying jobs, OPT students should not have to pay medicare ans social security taxes as long as they are on OPT. But will have to pay federal taxes. Wherever, u work try to get CPT if it favors on ur side.
But, hey! higher knowledge is always better, not moneywise though :(!

Good luck!