We are planning on cruising in the first half of December 2017 (unless they do Hawaii in fall 2017, then we will have to decide), so are looking forward to the release of those dates, whether that is soon or in say May. We have two OBB placeholders and plan to book on the first day the cruises are released: we know what room we want and want to ensure we get that; plus, the first day is usually (tho not always) the cheapest rates.
For hotels: you can book WDW hotels about a year out. If we know our dates we always book right away: we book a room we want that we are willing to pay rack rate for. We then keep an eye out for special offers and change the reservation to the offer if one comes up. In the past we have generally been able to get a nice room only offer, and once went with free dining (but we won't again: a room only works better for us). But, we do not COUNT on being able to get a special offer. For example for our December 2014 cruise, the nights at WDW before the cruise we got a RO offer for, but the one night after the cruise was in the blackout time with no special offers available (plus in that case the type of room we had is rarely eligible for a RO).
There are threads on here and other webpages that provide the dates for previous years' special offer dates; also, you can pay attention to what happens for 2016. I would also look up 2015 dates and maybe 2014 so you get a sense of the "pattern". BUT, there is NO guarantee Disney will decide to go with the same kinds of offers in the future. e.g. there is speculation on these boards that the end of free dining may be coming sooner rather than later. But there is no way of knowing for sure until Disney actually releases the specials for a given time period (or not).
As for the dollar... not sure anyone really knows where it is going to go, except that it will apparently stay down for a while. When we booked our Dec 2014 cruise about a year before the exchange rate on our CC was 1.19ish; by the time we took the cruise the exchange was in the 1.4 range !! Painful.
For our pre-cruise hotel, since we were room only we only had put down the deposit. When the dollar kept tanking and it looked like it would only get wrose, I called Disney and asked if I could just pay the full amount "now" instead of at checkin. they had no problem taking my money

I am glad I did though: original booking was at about 1.19; th full payment was at about 1.26; and when we actually travelled it woudl have been 1.4ish, so I saved a chunk ! Of course, if the dollar had gotten better I would have lost out on that gamble...
The exchange rate is part of why we are going to be cruising in 2017 instead of 2016 and 2017. We are also thinking of doing another B2B, only this time 2 x 7 nights; though expensive, it is still cheaper than doing 1 cruise in 2016 and 1 in 2017: airfare alone is close to $2000 for the two of us.
SW