Wizkids Rules!

According the rules insert for Secret Wars,

Epic Basic Actions can't and their effects can't be copied. You can only use or purchase 1 Epic Basic Action per turn. After using an Epic Basic Action, return it to its card. You can't purchase an Epic Basic Action unless you have an active character with purchase cost 4 or greater.

First an easy question. After following the guidelines for purchasing an Epic Basic Action, is there any requirements when you use it? Directly speaking, you no longer need the active character with purchase cost 4 or greater active for the use, correct?

Second, the insert states that the effects can't be copied, however there is precedent (https://win.wizkids.com/bb/viewtopic.php?f=10&t=15814&sid=5e89f688a882757074e43856d3b77f16) that abilities that copy an action are different from abilities that use the effect of an action.

Becky Lynch: The Man!
When Becky Lynch attacks, you may choose an unpurchased non-Continuous Basic Action Die and roll it. If it shows an Action face, you may use its effect immediately. Return the die to its card.

As such, could Becky Lynch: The Man! select an Epic Basic Action die to roll for her effect?

D'Ken: Obsessed
While D'Ken is active, if you take combat damage this turn you may use an action die from either player's Used Pile.

Similarly, could you use an Epic Basic Action die with D'Ken's ability? If so, that die should return to the card, correct?

After following the guidelines for purchasing an Epic Basic Action, is there any requirements when you use it? Directly speaking, you no longer need the active character with purchase cost 4 or greater active for the use, correct?

There are no requirements outside of any stated on an Epic Basic Action card and the condition of having a 4+ purchase cost active character is not applicable when a player chooses to use this die.

As such, could Becky Lynch: The Man! select an Epic Basic Action die to roll for her effect?
Similarly, could you use an Epic Basic Action die with D'Ken's ability? If so, that die should return to the card, correct?

Yes, to all three questions.

Note, if a player “uses” an Epic Basic Action die for either of these abilities, that player cannot purchase or use another Epic Basic Action die in the same turn, and visa-versa.