Do what's cinematic
While almost none of the specific example you gave actually works like that (which has been covered enough in Brian's answer and in comments on your original question), when you leave rulespace and enter improvisationland, the important thing is to have fun.
A lot of DMs use the improvised weapon rules for things like this. This is perhaps the closest thing to the rules, but I've always found it to be highly disappointing, as improvised weapons impose a severe attack penalty, don't necessarily use the right attack stat for your characters, and do frankly terrible damage compared to anything else your PCs could have done with their actions.
A good guideline is to make cinematic options -- a ballista on the airship you're riding on, knocking a pile of logs down a hill, blasting the ceiling of a cave to drop stalactites, knocking over a statue, or setting up a spike trap as you outlined -- either a skill check, an attack based on whatever stat someone can reasonably explain, or in many cases a d20 + a flat modifier. And damage should be somewhere between at-will and encounter-power tier, depending on the rarity of the situation.
Just to explicate where i'd use what, and reusing my earlier examples:
- firing a ship's cannon might be Level+5 vs fort and deal appropriate damage for a NPC ranged basic attack of that level, and might be available as a standard action as many times as any party member wants to do so. This option might allow strictly-melee characters to contribute meaningfully in an aerial or nautical battle with no melee combatants.
- knocking logs down a hill, depending on the situation could be either another flat bonus attack (if the logs were put there/prepared for this purpose, it would just be flipping a release and the logs would be essentially rolling the attack themselves) or a STR check/athletics check / other attack against the logs' support which subsequently leads to the aforementioned flat attack made by the logs. This could do more damage (i'd still use NPC damage tables if only for simplicity), as it could only be done once.
- for a spike trap such as the one you outlined, i'd have placing it be a skill check (anything you can reasonably explain) to set the DC of the acrobatics check required by the falling enemy to "miss" the spikes. If they failed and hit the spikes, the spikes would do 1x[W](whatever improvised weapon the spikes were made out of)per d10 of falling damage involved.
In situations where an enemy is indeed helpless, and thus eligible for telekinetic lift, it's hardly an issue to assume an auto-hit and instant fatality, if that's cinematic. This can't particularly be abused/reused to the point of imbalance, because helpless is a terribly rare condition to impose, and almost certainly leads to a gruesome death-by-coup-de-grace anyway.