B717 FLT CREW ENCOUNTERS OPERATIONAL DIFFICULTIES WHEN THEIR FAILURE TO PROPERLY INTERPRET/UNDERSTAND NOTAMS FOR DESTINATION RESULTS IN IMPROPER DISPATCH WITHOUT A SECOND FILED ALTERNATE.

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WE DEPARTED ZZZ1 ENRTE TO ZZZ2. THE CAPT WAS GETTING AN ANNUAL LINE CHK TOO. WE DEPARTED TO ZZZ2 WHICH HAD 1/2 SM VISIBILITY IN FOG. CTR ADVISED THAT THE RVR WAS 400 FT AND ASKED US WHAT WE NEEDED. THE CAT III APCH TO RWY 4 WAS UNAVAILABLE BECAUSE RWY 4 WAS CLOSED. TO LAND ON RWY 12R WE NEEDED 4000 FT RVR. WE WENT INTO HOLDING. OUR FILED ALTERNATE WAS ZZZ3. AT THIS TIME THE #2 FMS WENT OUT. SINCE THE ONLY WAY TO TUNE A NAV IS THROUGH THE FMS THERE IS NO MEL RELIEF FOR A TOTAL FMS FAILURE. WE CHANGED OUR ALTERNATE TO ZZZ4 AND DIVERTED. MAINT REPLACED THE INOP FMS AND WE DEPARTED FOR ZZZ2. BECAUSE RWY 4 WAS CLOSED; WE SHOULD HAVE DISPATCHED UNDER EXEMPTION AND HAD A SECOND ALTERNATE. ZZZ1 HAD GOOD WX AND WOULDN'T HAVE CHANGED OUR FUEL REQUIREMENT. THE CAPT DID CHK THE NOTAMS; BUT ONLY NOTICED THAT THE ILS TO RWY 4 WAS OUT AND NOT THAT THE RWY WAS CLOSED. WE WERE PLANNING ON THE RNAV APCH TO RWY 4 WHICH NEEDS 1/2 MI VISIBILITY. NOTAMS ARE WAY TOO DIFFICULT TO READ. WHY HAVE A PAGE OF NOTAMS CONCERNING RWY 4 APCH MINIMUMS WHEN THE RWY IS CLOSED? THE ENTIRE FORMAT IS DIFFICULT TO READ AND NOT USER FRIENDLY.