ACFT ENCOUNTERED SEVERE WINDSHEAR ON FINAL APCH AND ABANDONED THE APCH. DURING THE SECOND APCH; WINDSHEAR CAUSED AIRSPD INCREASES WHICH RESULTED IN INDICATED AIRSPDS ABOVE FLAP LIMIT SPDS. ACFT LANDED WITHIN THE TOUCHDOWN ZONE.

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DIVERT TO BWI BECAUSE OF FRONTAL PASSAGE WHICH RESULTED IN RPTS OF 30 KT WINDSHEAR AT IAD. ON APCH AT BWI; ENCOUNTERED WINDSHEAR; WHICH RESULTED IN A FLAP OVERSPD FOR FLAPS 5 DEGS. WE DID A GAR AND EVALUATED OUR OPTIONS WHICH TOOK INTO CONSIDERATION OUR DECREASING FUEL SIT; WX AT BWI; ELT AND DECIDED TO MAKE ANOTHER APCH AT BWI. WE ENCOUNTERED SIGNIFICANT TAILWIND ON FINAL; EXPECTING WIND TO SHIFT TO A HEADWIND. LANDED LONG (BUT STILL ABLE TO GET STOPPED WITH PLENTY OF RWY) DUE TO EXTRA AIRSPD; TAILWIND AND FAILURE TO GET FINAL FLAP SELECTION OF 30 DEGS INSTEAD OF 25 DEGS. IT WAS A VERY RAPID AND DYNAMIC SET OF EVENTS; SOME FAST DECISIONS WERE MADE. IN RETROSPECT; WE WOULD NOT HAVE CHANGED OUR LNDG ARPT BUT AN INQUIRY ABOUT LATEST SURFACE WIND WOULD HAVE BEEN IN ORDER. I NOTICED FLAPS AT 25 DEGS AT ABOUT 150 FT; CALLED FOR FLAPS 30 DEGS. CAPT SAID ROGER; FLAPS 30 DEGS; BUT NEVER SELECTED FLAPS 30 DEGS. FLAPS 25 DEGS IS A LEGAL LNDG FLAP FOR ACFT; BUT NOT THE BEST IN THIS SIT. THIS OVERSIGHT CONTRIBUTED TO OUR LNDG RIGHT ON THE LIMIT OF THE TOUCHDOWN ZONE.