CL65 CREW CLBED ACFT TOO HIGH FOR THE ACFT GROSS WT; GOT ON THE BACK SIDE OF THE PWR CURVE; AND EXPERIENCED STALL BUFFET AND STICK SHAKER IN ZMP CLASS A AIRSPACE.

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WE WERE CRUISING AT OUR FLT PLANNED ALT OF FL370 AND DECIDED TO CLB TO FL410. WE CHKED OUR STEP-CLB PERFORMANCE; WHICH WAS ACCEPTABLE (CLB RATE OF 110 FPM AT FL410) AND RECEIVED CLRNC TO FL410. WE SELECTED CLB THRUST AND CLBED TO FL410 AT 500 FPM. WE LEVELED OFF AT MACH .68 TO MACH .69 BUT CONTINUED TO LOSE AIRSPD. WE REQUESTED A LOWER ALT WITH ZMP; BUT WERE TOLD IT WOULD BE ANOTHER 5 MINS DUE TO TFC. WE NOTICED OUR POSSIBLE TFC ON TCASII AT FL390. APPROX 15 KIAS ABOVE THE LOW SPD STALL AWARENESS RASTER; WE NOTICED SLIGHT BUFFETING. WE REQUESTED A HDG SO WE COULD DSND AWAY FROM THE TFC. ATC TOLD US TO TURN R 20 DEGS. AS WE STARTED THE TURN; THE AUTOPLT DISCONNECTED DUE TO THE STICK SHAKER. THE FO IMMEDIATELY NOTIFIED ATC THAT WE COULD NOT MAINTAIN ALT AND NEEDED TO DSND NOW. ATC REPLIED 'IF YOU WANT TO DSND NOW; YOU MUST DECLARE AN EMER.' I INSTRUCTED THE FO TO DECLARE AN EMER TWICE; BUT IT WAS NOT CONVEYED TO ATC. WE THEN RECEIVED A TCASII TA (NO RA) AS WE WERE DSNDING. WE HAD THE TFC IN SIGHT AS WE STOPPED THE DSCNT AT FL397. ATC VECTORED THE TFC AND ASKED US WHAT ALT WE WANTED. WE TOLD HIM FL370. AFTER CLR OF THE TFC; ATC CLRED US TO FL370 AND DIRECT TO PIA. ATC ADVISED US TO CALL ZMP. I BELIEVE THE CAUSE OF THE PROB WAS INACCURATE CLB CHARTS WHICH SHOWED THAT WE COULD CLB TO FL410 FROM FL370; AND ONCE AT FL410; MAINTAIN A CLB OF 110 FPM. WE NEVER WOULD HAVE ATTEMPTED THE CLB TO FL410 IF OUR PERFORMANCE CHARTS INDICATED WE COULD NOT DO IT. THIS COULD BE PREVENTED IN THE FUTURE IF WE WOULD RECEIVE UPDATED AND ACCURATE STEP-CLB PERFORMANCE CHARTS THAT ACCURATELY DOCUMENTED THE CL65'S TRUE CLB PERFORMANCE AT ALT. THE TFC CONFLICT COULD HAVE BEEN RESOLVED IF THE FO FOLLOWED MY COMMANDS TO DECLARE AN EMER.