The first one is purely thematic: ranged weapons should be bows and crossbows and the occasional throwing weapon. Most of the ranged weapons in Descent 1 are wierd magical orbs or magic sticks or scarabs (do you throw them?)
One assumes you do throw them, if they're ranged weapons and not magic weapons. "Magic" attacks, thematically, are attacks where the primary damage source is raw magical energy (usually coming from a runestone or a staff of some kind.) The scarabs are magic items that you throw at people and then they presumably explode in a shower of magic beetles or whatever. Powered by magic, but the primary source of damage is beetles. There are also magic swords and axes that are (rightly, IMHO) classified as "Melee" attacks. I don't have my decks here to look through them right now, but I don't recall any particular weapon striking me as being in the "wrong" category. You just have to think about how the weapon COULD be used in the category it has been assigned to. And remember that "magic weapon" need not equal "Magic attack."
The second complaint is partially thematic, but relates to game mechanics: The overlord is always desperate, the whole traps, spawning and card mechanics reinforce an idea that the overlord needs to pull every trick out of his hat in order to have a fighting chance against the heroes. The heroes don't feel like their david desperately fighting goliath. They feel like they are goliath and the overlord is this petty nuisance. Possible fixes could include:
Include feats with the base game. (Means the heroes have tricks they can pull)
Make monsters more dangerous, spawning and cards less dangerous.
Limit Hero ability to get splash weapons/reduce splash weapons power.
Sounds to me like the Overlord in your game is spending too much time and effort trying to keep the starting monsters around for a turn or two longer. Monsters are expendable, and the primary source of monster damage (especially after the heroes get to Silver and Gold) will be spawned monsters, not the ones on the map. Accept this and let the starters die and you'll find the Overlord's side is much easier to manage. It's funny that you think the Overlord always struggles, since most people would agree the Overlord's learning curve is much easier than the heroes'.
As an aside, how would giving the heroes Feats in the base box help to fix the issue of the heroes overrunning the Overlord too easily? Doing that and making the Overlord's cards "less dangerous" would only increase that particular issue, as I see it.