"does everybody have to find their own "light", a weight that allows quality singles but heavy enough to get into same groove as heavy lifts?"
"I can honestly say that my PRs had no "groove" the were just grip and rip and hope to hold on without dislocating something or crapping myself"
***This is exactly why I think you should practice the full lifts as much as possible, if your body allows it. You need a motor pattern grooved in there. If you do this, you won't have to worry about shifting from one "groove" to another on meet day. Every lift will be the same.
"Obviously back squats, probably front squats? Pulls - deadlifts or just snatch pulls and clean pulls (I debate with myself about whether DL, even RDL are "specific"."
***Back squats definitely, front squats if your body cooperates. I would lean more towards snatch and clean pulls performed perfectly (with just a little more weight than your max SN and C&J) than DLs and RDLs. Pressing doesn't hurt anything, as long as it's not kicking the hell out of your shoulders or anything else.