Ok lets see. I haven't actually gone there yet, but I loaded it up in TES5Edit to take a look.
First of all, cleaning results:
UDRs
Spoiler Skipping: [NAVM:000F4C18] (in GRUP Cell Temporary Children of [CELL:0000979E] (in Tamriel "Skyrim" [WRLD:0000003C] at 20,-16))
Skipping: [NAVM:000FA72F] (in GRUP Cell Temporary Children of AutumnLodgeStablesixt [CELL:0000977F] (in Tamriel "Skyrim" [WRLD:0000003C] at 20,-15))
Skipping: [NAVM:000FA72E] (in GRUP Cell Temporary Children of AutumnLodgeext [CELL:0000977E] (in Tamriel "Skyrim" [WRLD:0000003C] at 21,-15))
Skipping: [NAVM:000FA1CD] (in GRUP Cell Temporary Children of aaaDragoniaExt07 [CELL:00009721] (in Tamriel "Skyrim" [WRLD:0000003C] at 21,-12))
Skipping: [NAVM:000FA1D0] (in GRUP Cell Temporary Children of aaaDragoniaExt07 [CELL:00009721] (in Tamriel "Skyrim" [WRLD:0000003C] at 21,-12))
Skipping: [NAVM:000FA1D1] (in GRUP Cell Temporary Children of aaaDragoniaExt07 [CELL:00009721] (in Tamriel "Skyrim" [WRLD:0000003C] at 21,-12))
Skipping: [NAVM:000FA1D2] (in GRUP Cell Temporary Children of aaaDragoniaExt07 [CELL:00009721] (in Tamriel "Skyrim" [WRLD:0000003C] at 21,-12))
Skipping: [NAVM:000FA1DB] (in GRUP Cell Temporary Children of aaaDragoniaExt06 [CELL:00009720] (in Tamriel "Skyrim" [WRLD:0000003C] at 22,-12))
Skipping: [NAVM:000FA1A7] (in GRUP Cell Temporary Children of aaaDragoniaExt03 [CELL:00009702] (in Tamriel "Skyrim" [WRLD:0000003C] at 21,-11))
Skipping: [NAVM:000FA1BB] (in GRUP Cell Temporary Children of aaaDragoniaExt05 [CELL:00009700] (in Tamriel "Skyrim" [WRLD:0000003C] at 23,-11))
Skipping: [NAVM:000FA1BC] (in GRUP Cell Temporary Children of aaaDragoniaExt05 [CELL:00009700] (in Tamriel "Skyrim" [WRLD:0000003C] at 23,-11))
Skipping: [NAVM:000FA1B0] (in GRUP Cell Temporary Children of aaaDragoniaExt01 [CELL:000096E3] (in Tamriel "Skyrim" [WRLD:0000003C] at 21,-10))
[Undeleting and Disabling References done] Processed Records: 21493, Undeleted Records: 0, Elapsed Time: 00:00
I know that deleting Navmeshes can cause crashes if another mod comes along and tries to touch them later, and TES5Edit won't undelete them. Might want to look into the best practices for dealing with this. (tbh I have no idea, ask Arthmoor maybe?)
ITMs:
Spoiler Removing: [REFR:0010EAA7] (places PickaxeMiningTableMarker "This should not be visible" [FURN:000613A7] in GRUP Cell Persistent Children of [CELL:0002D4E0] (in Blackreach "Blackreach" [WRLD:0001EE62]) at 1,5)
Removing: [REFR:0010EE41] (places PickaxeMiningFloorMarker "This should not be visible" [FURN:000613A6] in GRUP Cell Persistent Children of [CELL:0002D4E0] (in Blackreach "Blackreach" [WRLD:0001EE62]) at -2,3)
Removing: GRUP Cell Persistent Children of [CELL:0002D4E0] (in Blackreach "Blackreach" [WRLD:0001EE62])
Removing: [NAVM:000FA722] (in GRUP Cell Temporary Children of [CELL:00009740] (in Tamriel "Skyrim" [WRLD:0000003C] at 21,-13))
Removing: [NAVM:000FA723] (in GRUP Cell Temporary Children of [CELL:00009740] (in Tamriel "Skyrim" [WRLD:0000003C] at 21,-13))
Removing: [NAVM:000FA20A] (in GRUP Cell Temporary Children of [CELL:0000973F] (in Tamriel "Skyrim" [WRLD:0000003C] at 22,-13))
Removing: [NAVM:000FA20B] (in GRUP Cell Temporary Children of [CELL:0000973F] (in Tamriel "Skyrim" [WRLD:0000003C] at 22,-13))
Removing: [NAVM:000FA1CC] (in GRUP Cell Temporary Children of [CELL:00009722] (in Tamriel "Skyrim" [WRLD:0000003C] at 20,-12))
Removing: [NAVM:000FA1D9] (in GRUP Cell Temporary Children of [CELL:0000971F] (in Tamriel "Skyrim" [WRLD:0000003C] at 23,-12))
Removing: [NAVM:000FA71B] (in GRUP Cell Temporary Children of aaaDragoniaExt05 [CELL:00009700] (in Tamriel "Skyrim" [WRLD:0000003C] at 23,-11))
Removing: [REFR:0200CB18] (places CreatureSitMarker03 [FURN:0008CDE7] in GRUP Cell Persistent Children of DLC1VampireCastleZCell1 "Volkihar North Tower" [CELL:02007203])
Removing: [REFR:0010FC7B] (places MineOreBlackreach02_CaveGWall "Geode Vein" [ACTI:0010FC0F] in GRUP Cell Temporary Children of BlackreachSewer01 "Silent City Catacombs" [CELL:0007FCDD])
Removing: GRUP Cell Temporary Children of BlackreachSewer01 "Silent City Catacombs" [CELL:0007FCDD]
Removing: [REFR:0010FC7E] (places PickaxeMiningWallMarker "This should not be visible" [FURN:000E2BC7] in GRUP Cell Persistent Children of BlackreachSewer01 "Silent City Catacombs" [CELL:0007FCDD])
Removing: GRUP Cell Persistent Children of BlackreachSewer01 "Silent City Catacombs" [CELL:0007FCDD]
Removing: BlackreachSewer01 "Silent City Catacombs" [CELL:0007FCDD]
Removing: GRUP Interior Cell Sub-Block 8
Removing: GRUP Interior Cell Block 5
Removing: [REFR:000A3DE2] (places RiftenRWHallArch01 [STAT:000484C2] in GRUP Cell Temporary Children of RiftenRatway01 "The Ratway" [CELL:0003B698])
Removing: GRUP Cell Temporary Children of RiftenRatway01 "The Ratway" [CELL:0003B698]
Removing: RiftenRatway01 "The Ratway" [CELL:0003B698]
Removing: GRUP Interior Cell Sub-Block 5
Removing: RiftenRWRoomBEndCap01 [STAT:00098D91]
Removing: AltarMaraSpell "Blessing of Mara" [SPEL:000FB998]
[Removing "Identical to Master" records done] Processed Records: 21493, Removed Records: 24, Elapsed Time: 00:00
24 ITMs isn't bad for a mod this size, but still worth making sure you clean out.
Lets see what else...possible conflicts with the Draugr boots and College boots, but those are minor.
You modified a Bed record in a way I'm not entire sure is advised. FormID 000fedc8. Maybe should be an entirely new record, instead of modifying a vanilla one?
I've heard there are issues with changing the sandbox cylinder, but not enough to say one way or another if that is an issue.
Modifications to Light records could affect other mods that use those lights.
You edited DLC1VCSkeletonMage_Ambush [NPC_:0201830B] and reduced its aggro range to 0, could cause conflicts with expected behavior elsewhere?
You heavily modified Package record 000978e3, probably should have been a new form.
A Fireplace record now uses HD LOD Textures? Form 000c0c6e
Alright, thats what I can see in TES5Edit. Pretty clean mod overall, the majority of it is new records so that helps. Check out those modified Bed, lights, Skeleton and Package, those are most likely to cause unexpected issues. The Deleted navmeshes are the most likely to actually cause people's games to crash.
Once I've checked out the house I'll let you know my impressions. The courier letter is nice, though it assumes you are in fact the Dragonborn at the point where you get it. Not a big deal since skipping the main quest isn't something you should feel compelled to account for.