A few thoughts, yes. First, my background - I build and play acoustic resonators, biscuit, spiders and tricones - but not electric. If you want the amplified sound to sound like a reso, you need to pick up the cone - internal mics's, possibly a pieso in the saddle, or one of those little Lace sensors on the cone itself seem to sound the most "reso - like". When I hear a reso with a magnetic pup or a lipstick or something they tend to sound like an electric guitar.
The metal body is part of the whole sound that we have come to expect of, say an old National - it definitely colors the sound (I have both metal and wood bodied guitars). Even the type of metal - bell brass, steel - can affect the sound. NRP has clips of different body materials - might be worth a listen.
Next - most people who play resonators play at least some slide. For a slide guitar you really don't any string compensation (you are not stretching the strings) and you have the ultimate compensator on your pinkie. So most reso have the saddle at extactly 2X the distance to the 12th fret. If you want to add compensation you will compromise your slide playing. My tricone has just a hair of saddle slant since I play both fretted and slide but it will be a compromise.
Now to the trem (my disclaimer, I don't have one on my LP and really don't see a need for one). It will add a lot of complexity to building the guitar. Most resos are tailpiece and the break angle over the cone needs to be pretty shallow, particularly on a biscuit. Too much break angle, too heavy strings or tuning up to something like open A risks damaging the cone (don't ask how I know). If you are playing slide you will be varying the note below and above pitch so the trem is kind of redundant.
As to your idea about the metal insert for the biscuit - that might be a little tricky. First, most biscuits are maple with a maple or maybe ebony saddle insert. I do have a carbon fiber biscuit in one of my guitars - but it still have notches in the saddle for string spacing. The more mass you add to the cone the longer the attack and sustain of the note will be - tricones have longer sustain than biscuits for that reason. Therefore adding the metal mass might change the response of the cone.
John Dopreya is said to have experimented with metal saddle inserts on the early Dobros (brass, I think) and came back to maple as the best sounding. Don't know anything else about that, but almost all resos today use wood saddles.
Not trying to discourage you, but I think you should think through this whole design before you commit to it. If you do want to build a metal body there is a wonderful discussion of a tricone build archived somewhere here at MIMF. I had the wild idea once of building one out of titanium (I work in a metal fab shop) - would you call that a TiCone? Do a good side view of your guitar calculating neck angle, action height, break angle and cone well depth. Most resonators use neck sticks which sets the neck angle which sets the action (there is very little you can do at the saddle) but my last one was built with a standard bolt on neck. There are dedicated resonator building subforums at OLF and the ResoHangout - you might want to ask specific questions there
http://www.luthiersforum.com/forum/view ... 04&t=20333
http://www.resohangout.com/forum/
Good luck, post pictures, and if I can supply any information let me know
