Full Method, Splitting, Finalizing, Compressing

[Vincendre]

Hey,
I try to use this software since yesterday, with the BlackBox v2 Designer, to try to do few RePacks of my games, but I have few questions and I hope I ask them in the good topic :

1- I've tried to compress Final Fantasy V game (which size 1Gb) with the DLG_S_&_C v1.1 and with the "best quality" option, my setup file size ~660Mb.
But with the DLG_S_&_C v1.2, the same game with, this time, "Ultra Quality" (which takes very more time to compress), my setup file size is now 755Mb.

Does it's normal ? A Ultra quality compression it's better than the second option "best" I guess so why the size is bigger with this 1.2 version ?

2- By the way, Ultra Quality Compression is really the best option to choose for RePack some games ?
(I want to RePack my games, like BlackBox or RG Mecanics for my personal use and to share them easier with friends (And to learn too, I like to know a bit of everything)).

3- Usually, I just mount my ISO games and install them normally, and everything work fine with ISO disk.
But to create a RePacked Games, I have to compress installed data of a game etc.

But about Update or DLC, or even Mods, does RePacked game cause any troubles ? (I guess the awnser is no but I prefer ask this anyway)

Sorry for my English (I'm French)
And to ask so many questions, but I hesitate between keeping my ISO format for Games or convert them all to RePack version (for easier installation sometimes and to save some HDD space)
I want to understand I bit more about those things.

Thanks