If you just want access to the CG's and to have all of the achievements from the start, Modular Cheat Mod has you covered.
Download and install (as per the instructions on the post) and issue the following commands in the F10 console:
CheatUtils.unlock_cg
- Unlocks all 13 CG's. (If used in the CG room, leave the building and return for it to apply)
CheatUtils.unlock_ach
- Unlocks all achievements.
If you just want to play with a strong character, the mod also has you covered as you will be able to roll your own strong character from the start.
The only thing it can't help you with is having the quests pre-completed.
P.S: The unlock tool is only implemented as commands due to the code not working when the commands are issued from the cheat menu. I have tried, but no matter what I do it just refuses to work that way.