I'll try and shift the rest onto Exilian. I consider it quite badly written compared to things I've spent a decent amount of time on, but glad you're enjoying it - let me know what you think of the world and setting in particular and do ask any questions that spring to mind.
Magic - essentially this comes in two linked forms, illusion and summoning. So magic can't directly manipulate the physical world, it's essentially a form of communicating with the "astral" - a sort of secondary universe that brushes up close to our own and supplies a lot of the necessaries for conciousness. Summoning basically opens/finds a hole between the universes big enough for some raw conciousness to get through and imbue physical forms with a thinking mind for a time. Illusion uses the astral universe as a shortcut straight into someone else's (or lots of other people's) head or heads, allowing the manipulation of their thought processes.
Hovercraft are probably a no, submarine yes but exceptionally rare, a decent submarine would be considered cutting edge military/spy hardware.
Dragons... I'm saying nothing yet.