Is there a way to keep henchmen (Daelan red Tiger) from running ahead and causing mayhem and spoiling my plans? Playing EE version

From what I know, there's no way unless you're up for some modding of the AI scripts. You can also find some finished mods for the AI of henchmen such as this one: https://neverwintervault.org/project/nwn1/hakpak/original-hakpak/henchman-inventory-battle-ai-mod. But I doubt it'll help you with this problem.

Try telling him to stay in place and not move from his spot (I think the shortcut is V-W-X, or else look for it on the radial).

They don't always listen when enemies are close, especially not if you just tell them to follow vs. telling them to stay put, so be prepared to repeat your commands, if he tries to run ahead again (the keyboard shortcuts are useful for that). Can you talk to him and change his tactics? Maybe there's something in there that makes him less likely to attack enemies in sight?

When playing with Daelan, half of the time I'm telling him to stay where he is. This allows me research the area, disable traps, loot, and so on without worrying about what Daelan is doing. If I encounter some easy enemies I fight them alone; and if the enemies are tough, I run back to Daelan and tell him to defend me, or attack the nearest enemy.

That was generally my tactic as well when playing a sneaky character. I'd just move my peon up closer every now and then so I wouldn't have to lead the harder enemies back so far. I always considered them as just hired guards for backup every now and then.