Deck beams are usually "let" into the sheer clamp and notched to receive stringers (if they're deep enough).
Yep, longitudinal stringers are beveled to match the crown of the deck. This might seem difficult, but generally it's not and usually it's the same angle the full length, so you can do it on a table saw. If they were oriented radially, they wouldn't be working as the upper flange of the "beam" and will likely tend to deflect under load, because they're being pressed down at an angle to their vertical orientation. Picture a 2x4 on edge, straight up and down, holding up a weight. In column this isn't an issue, but once you introduce the radial orientation, the load in now is trying to twist the stringer out of it's orientation, rather then just bear the load as a straight one will.
The additional crown wouldn't decrease the beam/stringer strength, it would likely improve it. Curved surfaces are inherently stronger then flatter panels. If the crown is 12" you'll probably need to have some bent or laminated longitudinal stringers. Maybe take the crown as tall as the old cabin and call it good.
Would you install a 1X2 oriented horizontally under and glued/screwed to the vertical sheer clamp to give the beams/stringers something to rest upon
Yep, as you and I have discussed previously, glue a perimeter "sheer clamp" all around the hull shell edge. It'll reinforce any exterior rub rail you install, offer some beef to the chain plates, makes a good nailer for the edge of the decking, provides a place for the deck beams to land, etc.
About the angled beam pockets. This is a traditional method and it has a lot to recommend it. When the beam is cut to the right length, it fits perfectly, if not it's too tall or too low. If it's too tall, you just shave it until it drops down where it needs to be. If it's too short, then you can shim it up with a sliver of wood and get it right. The slope also provides a natural path for moisture to drain out of the joint, if it happens to get in there, so it's less likely to rot. In real life, you'll glue and screw the beams into the clamp, so not as big a deal for rot and shedding water.
More Electras? You're lucky to have them, though some might suggest you're into pain, maybe both. Think light and strong on this one, so you can stomp on the others.
When plywood is epoxied to things like 1x2's and sheer clamps, it becomes incredibly strong. A piece of 1/4" plywood epoxied to a few 1x2's and a few 1x2 topped bulkheads, is more then strong enough to jump up and down on after winning your first match race. There's no place for 2x4's or 2 x anything on this boat. With the exception of the aft cabin bulkhead, which also could be just 1/4", all the plywood you'll need can be 1/4" stuff. The ring frame and the cabin bulkhead need to be pretty good plywood, so error on the thicker side if it's Lowe's/Depot stock, but the cockpit furniture can be cheaper, it's just got to hold your butt up.
Hey, a sanitary thread again. We can get back to being reasonable and talking in a normal tone of voice again. Thanks Mr. Moderator, it's not something I would of thought of, a good idea though.