You can call 12 months out at your home resort and 8 months out if you want to exchange somewhere else.
Like Denise, I haven't heard the reservation number called Concierge. PErhaps they are talking about the concierge service to arrange say for your refrigerator to be stocked up when you arrive or to make other travel arrangements. I don't find that particularly worthwhile. It is nice to have your refrigerator stocked but I generally prefer to do my own shopping. As far as travel arrangemnts I have other services to do that.
I do find hotel points worthwhile. I don't exchange for them much since I also use my Starwood AmEx, but there are some high end hotels, particularly overseas, that can be worth the exchange. It is also nice to have the option of getting the Starpoints should you not be able to use your timeshare and not want to go through the hassle of renting it out. If you reach platinum level with Starwood (either through stays at Starwood hotels or by becoming 5 Star Elite at SVO), then the suite upgrades do make things worthwhile. Whether paying the extra money to buy from the developer is worthwhile to get this benefit is something only you can answer. If you know you will want more than one unit I'd say definitely buy resale first and buy from the developer second. For just one unit, I'd be less definite. I bought from the developer before ever finding TUG and while I could have saved some money, I don't really regret it. The enticements I got at the time in the way of Starpoints (worth $0.02-$0.05 cents each to me) reduced the price difference significantly and the ability to convert to Starpoints was valuable to me. Not sure what they are offering these days.
I don't like Interval International, especially if you buy a higher end property like WKORV, since comparable properties never seem to be available for exchanging.