AGE 73 WORKING FULL TIME

CAN I MAKE CONTRIBUTIONS TO MY EMPLOYERS EMPLOYEE 401K PLAN?

AM I REQUIRED TO MAKE RMD FROM MY EMPLOYERS EMPLOYEE 401K PLAN BEFORE I RETIRE?

IF I AM PART OF 457b PLAN AND HAVE AN IRA AM I REQUIRED TO WITHDRAW PER THE RMD REQUIREMENT FROM EACH FUND SEPARATELY OR CAN I CHOOSE TO DETERMINE THE VALUATION OF BOTH FUNDS AND WITHDRAW THE TOTAL RMD REQUIREMENT FROM JUST ONE FUND?

THANK YOU