I could write a dissertation on this subject, but don't have the time. So this will have to suffice:
1. Yes, there were other stations that licensed the PAMS packages that originated at and for WABC. (In fact, that was part of the deal with WABC. Sklar worked with Bill Meeks at PAMS to create jingle series that he thought would work at WABC, and they then got market exclusives on them in NYC. PAMS would then customize the package for other stations in other markets, and a lot of the development costs had already been underwritten by ABC. But ... no, these other stations were not WABC clones. Nobody was a WABC clone. It was a unique station, with a format that was superficially imitatable, but not really. Because it was more than the sum of its parts. The jocks, the music research and selection,the news operation, that unique sound, the jingle packages (which sometimes had cuts from earlier generations of packages intermixed with the current package), the aural cacaphony of jingles upon jingles over ramps, the way the jocks interacted with each other, the management, the sales force, the rules for how all this was knit together. I never heard anyone do it quite the same, or quite as well.
2. WOR-FM, as much as I liked both the pre-Drake format and the Drake/Sebastian Stone 50% Gold format, was not a direct competitor to WABC. It wasn't a level playing field in 1967 (or the subsequent half-dozen years). WABC's jock roster was unusually stable. WOR-FM was a revolving door of California guys who largely didn't like NYC and wanted back to the West Coast. And who weren't paid competitively, because it was still FM. Maybe if Drake had been able to get his hands on WOR-AM, with its 50Kw signal, it might have been a more even playing field. Or it had been 1977, when FM was largely on that level playing field with AM. But that was not to be, because RKO General was not run by idiots, and no matter how big Bill Drake's eyes and ambition were, they were not about to kill their golden goose in Market #1 for him.
3. Drake was an easier format to clone. WFIL in Philly was a pseudo-Drake station, but Drake never consulted there and it still was highly rated, with great talent and excellent format execution. That was true in a number of other markets. They may not have had the Drake fairy dust sprinkled on them, but they still managed to clone the format and succeed. TTBOMK, nobody ever had a success like WABC, even when a station like KYA in SF hired as their PD the former Asst PD from WABC, Julian Breen. They held their own against KFRC, until they finally collapsed in the early/mid '70s. Mike Hagarty has documented that competition very well in an earlier thread on the SF or LA board. (Can't recall where it is, but seek and ye shall find.)