The only one of those questions that I can answer for you Saric is number 3.
The Comet is a rigid airship with a duralinium alloy frame. I would expect smaller craft to be dirigible or frameless, but once you go over a certain size an airship basically has to have a frame of some kind. I can go into agonizing detail as to how I designed the Comet if you would like.
Given the size of the Hindenburg the idea of a dirigible being a smaller
craft fills me with a certain amount of dread...
On a more on topic note is the lift gas dispersed or in a centralized location and is it one big bag or multiple smaller 'cells'?
Wild and loony contraptions are definitely welcome! I think it really depends on the type of mad Sciencery you wanted to do. Fringe science is one of those.. "What did you have in mind" sort of deals. Were you thinking more crazy inventor of gadgets or something more like Frankenstien type? There is lots of room without getting too carried away.
The same with magic. It's more of the Victorian superstition and spiritualism.. Which offers plenty of room, without stepping over the line. So, when you say Alchemy... What exactly were you thinking? I can tell you something along the lines of Full Metal Alchemist would be considered too much and not in line with feel of the game. Magic and supernatural is extremely subtle and often rumor and those that "practice" are usually seen as charlatans.
Lighting cannons, inferno pistols, and fun with super-magnets was more what I was thinking in terms of 'Mad Science!'. I've got a couple of ideas bubbling away but this one would be the kind of guy who invents a ray gun and simply has
to test it out on a real target... only to stop and start tinkering with it in the middle of a firefight.
Alchemy can go several different ways depending on what you'd allow; potions and elixirs that strengthen you temporarily at the cost of a prolonged weakness; extracts and 'essences' that allow you to make salves that heal or temporarily animate objects with the 'essence' of life, or a glass ball that glows continuously because it contains the 'essence' of light; or the more extreme type that gets into the creation of homunculi, elemental conversion (the whole lead to gold thing), or the philosopher's stone. Obviously the last sort is unlikely but the potions and extracts have effects close enough to what could be accomplished by more ordinary 'science' for there to be doubt about the legitimacy of his work. After all, how do you tell the difference between a glass ball containing the 'essence of light', a lightbulb containing a noble gas, or a sphere containing some slow chemical reaction? Or the difference between a potion that triples your strength or speed for fifteen minutes only to leave you weak or slowed for an hour or two and some mixture of drugs like opium and caffeine? It would have more obvious effects, but the very nature of those effects would raise doubt as to the true method
being used to achieve them. A character working the Alchemy angle would likely be an artillerist, whose always coming up with new shells or warheads, but whom can be counted on for a vial of smokescreen or sleeping gas when things get up close and personal.