Here's the last part of my answers to the 20 questions:
15. How are traps located? Description, dice rolling, or some combination?
5+ on d6 when blundering along or to notice hidden clues when moving carefully. Other actions make traps noticeable without rolls: see my post on search techniques.
16. Are retainers encouraged and how does morale work?
Get retainers, get hirelings! Typical hirelings desert on 5+ (on d6) when any hireling is injured (use damage roll,) or when facing magic, supernatural, or superior forces (separate d6 roll.) Extra roll if leader seems to be defeated or betrays them, or if party takes 50% losses, and again at 90% losses. Loyalty determines morale adjustment.
17. How do I identify magic items?
Standard spell research rules, for safe ID. Otherwise, trial and error.
18. Can I buy magic items? Oh, come on: how about just potions?
If you can find an M-U, you can buy scrolls. Potions usually require a wizard, who is much harder to find, but a priest may have blessed healing potions. Otherwise, you must commission magic items from a wizard.
19. Can I create magic items? When and how?
M-Us can make scrolls at any level, 100 gp/spell level. Otherwise, only wizards can make items. Use standard spell research rules.
20. What about splitting the party?
Probably not a good idea, but you can risk it. Avoid secret communication whenever possible.
I won't cover searching for traps, since I've covered it in detail earlier. The d6 roll is basically a save, not a skill roll. The morale rules are standard, except that I've switched to 1d6 to make such rolls easier; I can use the damage roll for the first person struck to determine what the hirelings do, and if there are large groups, roll a handful of d6s, 1 per 5 hirelings, to see how many bolt. I also use this as a "following orders in combat" test, when things get confusing. The TPK featured the fleeing hireling not dropping a bag of treasure that the players suspected was cursed. He didn't register what he was hearing for a while.
The magic rules are mostly pretty standard, except that high-level NPCs are rare and I've added the Holmes modification to scroll creation.
If the players split the party, I try not to use note-passing or pulling characters aside for secret sessions. I don't generally care if some players hear the description of a monster only one character can see; if they're fairly close, I assume there's some shouting, and if they're far, the other PCs can "on a hunch" run to help another PC. It keeps everyone involved. The recent posts on doppelgangers and possession indicate some of my thoughts on how to avoid secret communication even in more extreme situations.