Btw, I'm compiling a three-part guide to the game in the rest of this subforum, so if you ever get a chance to check I haven't said anything stupid in those threads please do take a look
I few things you can add:
Goblin Bomber can occasionally drop a bomb right next to him if you're sticking too close to him for a longer period.
The "official" goblin unit names are: Goblin Defender (sword+shield), Goblin Berserker (axe), Goblin Warrior (club), Goblin Shaman, Goblin Blaggard (bombs). I'm not sure if Blaggard is a good name, what do you think about it?
The "official" dungeon unit names are: Thug (mace), Thief (twisted knife), Brigand (shielder). I'm not sure these are the best? Maybe I should switch to the names you used.
A good weapon to take down Orcs are the bombs or melee weapons with knockdown ability (Warbreaker, Earthquake Staff, Twisted Knife). The same weapons are also useful against shielded enemies (Goblin Defender, Guard Captain and Brigand).
The get the thief off your back you can try to get hit deliberately (buy an enemy or a trap) or use a dashing rage attack with a melee weapon. With some precise positioning, you can get the floor spike trap to only hit the thief. In co-op games, the other player can hit the thief. Thieves are very useful if you have the Avarice curse. You can use them to get rid of unneeded weapons and items.
Skeleton Sword has a "tetanus infecion" attack that manifests in poison+muscle spasm effect. Hiccups also result in muscle spasms.
Skeleton Archers have no negative effect, except really high arrow damage that can often one-shot the player.
Vampire is actually a Vampiress. They don't have any boosts. They have a two-stage attack (hit + uppercut) which triggers if the initial attack succeeds.
One of the simple ways to kill a Bushido is to use the Meteor Staff + Voodoo doll. Drop a meteor on the shop keeper. As soon as Bushido comes out, mark him with the doll and drop it. Then just keep dropping meteors on the doll until he's done.