B737 CREW CONCERNED WITH TFC SEPARATION WITH REGARD TO THE LEAD TURN DURING DEP FROM KRNO.

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FLT WAS CLRED FOR THE WAGGE TWO DEP TO 15000 FT OFF OF RWY 16R FOLLOWING LIGHT CIVIL TWIN THAT DEPARTED 2 MINS EARLIER OFF OF RWY 16L. DUE TO THE SPD DIFFERENTIAL; OUR ACFT WAS ABOVE AND ABEAM THE TWIN WHEN THE FLT PATH DISPLAY DIRECTED OUR ACFT TO LEAD TURN THE 'WAGGE' FIX IN ORDER TO ESTABLISH THE 050 DEG COURSE TO 'JERGA' AS PER THE DEP. AS I WAS WATCHING THE TWIN; I COUPLED THE ACFT UP TO THE AUTOPLT AND HAD ENGAGED LNAV AT ABOUT 9000 FT TO KEEP MY FOCUS OUTSIDE ON THE TWIN. WHEN THE JET STARTED ITS TURN TOWARDS 'JERGA;' I QUERIED DEP AS TO THE ALT THE TWIN WAS CLRED TO AS OUR PROJECTED FLT PATH TOOK US RIGHT OVER IT. DEP STATED THAT THE TWIN WAS VFR AND HAD NO LIMIT ON ITS CLB AND THAT HE EXPECTED US TO FLY TO THE 'WAGGE' FIX BEFORE STARTING OUR TURN; BUT TO GO AHEAD AND CONTINUE OUR TURN L TO 50 DEGS AND RESUME THE DEP. I DISCONNECTED THE AUTOPLT AT THIS POINT AND PULLED UP AND BEHIND THE TWIN AS I WAS CONCERNED ABOUT BEING BELLY UP TO AN ACFT WHOSE INTENTIONS WERE NOT CLRLY KNOWN TO ME. I THEN QUERIED DEP AS TO WHETHER 'WAGGE' WAS A MANDATORY FLYOVER FIX BECAUSE IT WAS NOT MARKED AS SUCH ON THE CHART. DEP STATED THEY DID IN FACT EXPECT US TO FLY TO THE 13 DME FIX BEFORE TURNING USUALLY. ALTHOUGH THERE WAS NO DANGER OF COLLISION; AS I DO BELIEVE WE HAD AT LEAST 2000 FT ON THE TWIN; SITS LIKE THIS ARE A CAUSE OF CONCERN FOR ME. USUALLY THERE IS SOME SORT OF POSITIVE RECOGNITION BTWN THE 2 ACFT INVOLVED IF THERE IS TO BE MUTUAL VFR SEPARATION IN EFFECT. THE HAIR ON THE BACK OF MY NECK STARTED TO RAISE A LITTLE ON THIS ONE. IT IS STANDARD PROC FOR IFR NAV TO LEAD TURN FIXES UNLESS SPECIFICALLY PRINTED OTHERWISE. IN THIS CASE THE 114 DEG L TURN AT 250 KTS REQUIRED ALMOST A 3 NM LEAD. IF THIS IS NOT WHAT DEP WANTED; THEN I THINK STANDARDIZED NOTATION WOULD HELP CLR THE PROB IN THE FUTURE.