Most Furuno FA-150 failures hit the FA-1502 display, not the FA-1501 transponder. Identify the failed unit by symptom (dark MKD = FA-1502; no own-ship AIS = FA-1501), then swap only that box. A reconditioned FA-1502 needs no MMSI re-programming; a replacement FA-1501 must be re-programmed with MMSI, IMO number and voyage data.
No. The two boxes are independent. A reconditioned FA-1502 display will pair with your existing FA-1501 transponder, and vice versa, over the standard IEC 61162-1/-2 serial link.
Yes, when IMO MSC.74(69) and IEC 61993-2 type-approval is intact and the test report covers TX/RX, GPS lock and DSC Ch 70 channel management.