Typically what are the room rates/discounts for AP holders? I am booking for the end of next April/beginning of May and am wondering if it is worth me buying an AP.
Don't buy an AP figuring on getting a discounted room. That is a perk which may or may not work out for you. If you happen to be buying one anyway, or will break even, yes. But an AP will not guarantee a discounted room.
Here is a website that gives you history of Disney's discounts. There are no guarantees. And this year has been busy, so they probably will offer less discounts in the future (my guess).
You don't need an AP to book the reservation. So you can call for prices when they come out.