Alan, What is the expected completed cost? And I have some thoughts on various aspects.
From 600k€ and up depending on fitout.
How far aft does the bimini extend (I would suggest covering the dinghy completely
It goes back to the Targa, can be full or partial as shown. The targa extends well aft of the rear cockpit seating.
What would be the purpose of extending it to cover the dinghy? It won't prevent waves coming into it.
As the dinghy does not hang on davits, and there is storage for the 15-20 hp outboard under one of the forward hatches, you can just invert the dinghy.
2) Are you thinking of a variant with out the forward steering positions?
No way on this size boat. This is one of the key features of the design. There are plenty of other designs that use this space for a couple of double cabins. This is a comfortable boat for 4-6 people at most with space and load carrying ability for any desired extra equipment within reason, yet will retain great light wind performance.
3) Do you have the pro's and cons of the bi rig?
This is material for a complete thread, but in short:
Cons: Abnormal looks.
Slightly heavier than a single aluminium mast set-up.
Pros: Smaller sails are easier to handle.
Can be reefed at any angle. Not like standard rigs where you need to come into the wind to reef, which can be dangerous in certain conditions.
Safer due to no reliance on stays, toggles etc. One component failure on many boats will bring the rig down.
Flexible masts for added safety - automatic depowering in gusts.
Lower center of effort = lower heeling forces = increased safety.
More efficient rig.
No "sailing at anchor"
Easy to handle loads, no need for massive crossbeam to handle rig loads - so lighter boat that again needs less sail area to perform.
No forebeam required = less weight forward = less pitching
Booms can be let right out for easy downwind sailing.
Then there is the perceived disadvantage of one sail blanketing the other. This also happens with the traditional bermuda rig when the main blankets the forward sail.
On this design the rigs have a relative high aspect ratio (short boom compared to mast height) This cuts down the amount of blanketing, but as the boat is fast, one can overcome this by increasing speed and pulling the relative wind forward, or else trim to let one sail "feed" the other.
Blanketing the leeward sail can also be used to drop speed quickly, as can just letting the masts cock into the wind, so you can reef at your leisure.
4) Have you thought of a galley down config?
Yes, can easily be done on the starboard side, but to be honest, don't understand why one would want to be down there.
With this design, you can cook and keep a good lookout - boat is designed for short handed sailing

so cook can also be watchkeeper.
However she does look great and I like a lot about the design
Peter