I can't help you with most of that but I can take a stab at a couple of them.
1) I'm sure somebody must have stayed in the room you're asking about

, just not me
2) There was, then there wasn't and now there is again although they may not be calling it a chica discount this time around. I believe the rate is now 25K colones or just over $46 at today's exchange rates
3) "Best" is always subjective and YMMV. Best looking talent where you can go without getting ripped off too badly is probably Pantera Rosa and/or D'Pelufo. Best in terms of decent talent with relatively cheap sessions available in the club would probably include Le Grillon, Arcada and Molino Rojo. But you don't necessarily have to pick any one club to go to. For example, the last 3 places I mentioned are all reasonably close together. You can walk (carefully) between Arcada's and Molino. Le Grillon is only a few blocks away, but you'll probably want to take a cab between there and the other 2 clubs since you'd be going there at night when that area is not so safe to wander around.
4) Don't know but I'm sure mopeds must be available.
5) Again, don't know of any. BTW, research is fine but as far as wanting to get everything reserved now, that is not really necessary for anything other than the hotel room that you asked about in #1. Any MP's, strip clubs, tours or moped rentals can easily be booked when you get there.
6) Again, not sure. It was last reported as of last summer the answer was no, however the discount was never that huge anyway and if you're going to Jaco you're probably going to go there anyway. I suggest you bring your card, show it to them when you get there and ask them directly. It also wouldn't hurt to act real disappointed and angry if they tell you know. I doubt that would change much, but it couldn't hurt to let them know that some of their customers might be happier, stay longer and spend more money if they brought back the meager discounts they used to offer.