Breezehome where do I find the Exterior for this home in CK. I want to add a few things like plants ect,ect.

I own Lakeview Manor and like to know how do you rise or lower the ground. I don't mean stuff like rocks, plants buildings ect, just the ground so I can lay some parts flat.

Also if I remove that npc just north of Manor (The one that keeps walking around them bones on a table) Between Manor and the lake.Will it be safe or is he part of some quest. ?

Thank you in advance doe any help.

Edit: Please note I got steam version.