Hmmm... If you have a "new style" forestay you should not need to make additional adjustments with a chain plate or other type of adjuster ... this should only be a requirement for the guys who use the shorter "new style" shrouds in combination with the "old style" (shorter) forestay. Here a chain plate can be used to make up for the lack in length of the old forestay.
Question 3 .... The cut of a jib on a Hobie 16 was modified with introduction of the shorter shrouds (I guess in the early 90's) If you rake to an extreme (block to block while using some type of low profile mainsheet system) you will run into a problem where the clew of the "old style" jib will be relatively further down and slightly further back - causing problems sheeting in , especially when the jib traveler in all the way in. To compensate for this you could try modify some hardware -using some type of low profile block on the X bar, double pin the shackle at the clew to move the blocks closer to the jib (or even come up with some idea where the axle of the block would go threw one of the holes of the clew plate). Or you could get a new jib and a X bar with integrated traveler track ... OR… do not rake to the absolute max. You will be surprised what mast rake will do to your helm.

Patrick