This is from the 1420.1B:
"Graduates of the STA-21 SWO (ED option) will be designated as ensign, U.S. Navy, SWO student, designator 1160, with an additional qualification designator code line of accounting upon graduation from college/university. These officers are assigned to division officer afloat duties on a fleet unit where they will complete an initial URL experience tour, qualify as SWO, and be redesignated as SWO (1110). Upon completion of SWO qualification, and at the completion of their second division officer tour and favorable record review screening by the engineering duty community manager will automatically be redesignated to 1460 without board action and will be assigned to future duties as a special duty officer (engineering duty).
(2) Officers who no longer desire to execute their option to redesignate to 1460 shall submit a letter to NAVPERSCOM (PERS-412) via NAVPERSCOM Head Engineering Duty Officer (PERS-317C) stating their desire to remain SWO. The letter must be endorsed by the officer’s CO."
Basically, the option to go ED is automatic after completing your two DIVO tours and getting your SWO pin. You can also choose to request to stay URL SWO but I don't know why you'd want to, unless you really want to command a ship someday. This is an awesome option but it's extremely competitive. Most years there are only one or two spots and over 30 applicants. Not trying to discourage you but it's something to keep in mind. I changed my program option more than once as I learned more about each program. As for the Masters degree, they can send you to get your Masters that's not limited to SWO/ED. I know the
Graduate Education Voucher Program is available to URL officers and there may be other programs too.