Lets say I add a new mod or delete one. What should I do with the Mashed Lists.esp from there? If I add a new mod, do I just need to do what I did the first time and import mashed lists or should I uncheck it, delete it, and then place the un-imported original in the data folder and re-import everything? Then the same for if I remove a mod, do I just click import mashed lists and it updates or do I have to export the leveled lists that came with the original mod from it? Thanks for reading and help would be appreciated.

I'm wondering the same thing for Merged_Objects.esp. When adding esp/esm's, do I just recreate one and overwrite the old one in TESTool or is there a procedure I need to follow. For deleting esps too.

EDIT: Also, is it safe and/or necessary to create and maintain a Merged_Dialogs.esp along with Merged_Objects.esp and Mashed Lists.esp?

After adding or deleting mod, I've just recreated Meshed List or Merged Object and evertything worked fine. No need to delete, export or something like tat.

I heve read that you should avoid using Merged Dialogs as it may cause problems.

When you say you recreate the Meshed List. Do you mean just right clicking it and selecting import merged lists?

Okay, I won't use Merged Dialogs. Thanks for the reply too.

Yes, just rigth click > Import > Merged Lists.

Okay, I'll get to it. Thanks for the help.

No.
Do not use Merged-Dialogs. It is well known to break quests.

edit: oh, that question was answered. I missed that part.