1) The standards for all races are Frigates, Destroyers, Light Cruisers, Heavy Cruiser, Battlecruiser, Dreadnaught and Battleships. Now that is not to say there are many subclasses within these designations IE scouts,escorts,drones,war refits,command, torpedo etc. AND many special role ships as well
2) EACH ship's weapon layouts are unique to their role and each race uses it's own heavy weapons, not to say that some species use the same ones but there are exceptions.
3) That would depend on each individual ship and race affiliation and that's wayyyyyy too long a list to post.
4) Any mission questions should be addressed in the Mission and Scripting section here at dyna, those peeps can answer any questions you may have on the subject.