Patience what the- I hope people will give you some of your answers. I'll attempt on some. You asked about links..There is one by Dionysus Bachus on his Royal Corsair build thread here where he has some good pictures showing how to make fiberglass gear doors. It is a long thread, but a lot of golden nuggets on building these classic built up scale planes (and truly inspirational). You can't rely on the resources included in Royal kits to solve your questions (obviously), these things were definitely meant for builders. The thinking and creativity required to acheive your final desired results is certainly in YOUR hands..Ha ha. THAT's the fun of it. I would replace any pushrods in an old royal kit with modern ones (someone please come up with suggestions here). I think Century retracts or Robart's are obvious choices on your retract question (lots of pre-planning required). You'll need to figure out where all your push-rod holes, pneumatic air-line holes, e.t.c. need to be drilled before you start framing(and don't forget internal receiver-antanae routing if you so choose, and are not on 2.4 mhz yet). The hardest part on these planes is that you have to think and pre-plan for yourself! I'm sure you notice that these Royals don't build flat on the board with "jig-tabs" for wing ribs, and half-shell-on-the-board fuselage construction. You'll need to draw centerlines on all ribs and fuselage bulkheads and than secure them to your work surface somehow (maintaining centerline relationships). I like the idea of tack-gluing 1/4 inch balsa sticks between ribs and work surface, as well as between fuselage bulkheads and work surface, measuring carefully for overall straightness before planking with sheet balsa. I don't know if that makes sense (I assume you haven't framed yours yet). Counter to your nickname here, you will need to contemplate, and have PATIENCE to come out with a decent result with a Royal-type project. Good luck, and don't hesitate to ask any of us here for advice! You also asked about radio and servos: I have a somewhat older 7 channel PCM Futaba that I love (FPT-7UAP and can convert to 2.4mhz), but all the major brands are good. I don't have experience with the new 2.4 spread spectrum radios, but it seems to me that has to be the way to go(yes, get ready to drop a grand). Servos have become a major topic in themselves. Look at Tower Hobbies charts for Futaba to get an idea of all their choices!!! In my opinion the choice of aileron and elevator servos is the most important. Get expensive high-torque/high speed coreless servos here (40 to 100 oz./in., and .20 sec/60 degrees or better on transit time). The one thing that is never mentioned in the specs, is current drain! Digital servos are great, but do have a high instantaneous current draw as I here; more importantly, digital servos are much more expensive. I wish I could tell you on that, but only have those specs after I buy the servo (Current draw is documented with
some of their products). I like the Futaba 9402 for aileron and elevator. Specs as follow: .10 sec/60degrees transit time (very fast), and 111 oz./in. torque (extremely strong for the size and speed). They warn you about current drain (at START as they put it), but perhaps not as bad as digital ones(I don't know). This is a coreless motor with metal gears for strength and low backlash(slop). Other servo choices should be based on size, weight, torque-required, and cost. These are just some of MY suggestions, others here may have helpfull opinions I hope. Lastly..Go for it!
Just reading this response may require PATIENCE ha ha! Hope it was helpfull. Can any one else fill in?