Name: TR_Showcase
Clean: you have made your file dependent on TR_Mainland.esm. The only .esms that should be dependencies are Tamriel_Data.esm, Morrowind.esm, Bloodmoon.esm, and Tribunal.esm. Clean this dependency out with Wrye Mash.
Lighting: Ambient lighting settings are good. The fog settings need to be higher and have a density of 0.75, take a look at other vanilla ints for this setting. Good that the sunlight settings are low, but I’d bump them up just a little bit.
Northmarker: present, rotation is irrelevant
Fits exterior: good, although the basement can stand to be better aligned with the building. This would minimize problems like overlapping with other basements for claims in the future.
Pathgrid: good
Illegal to Sleep Here: no, incorrect. It should be ticked if this is in a town or city.
Gridsnap: good

Bleeders:

Furn_web00 (x2): it’s okay to have these bleeding into things, but this goes straight through a beam and thus looks weird. Rotate/place them in such a way that they don’t bleed straight through the wood beams.
com_sack_03_saltrice_10: sacks should bleed with their flat side, but for this, the bottom part should not be bled into the floor.
furn_de_tapestry_04: this one (on the upper floor) is bled heavily into the wood beam. Move it up so it’s going into the adobe, and make sure that the rope doesn’t bleed. I’d move all the tapestries that are like this up a bit, but they’re technically not all bleeding.
furn_de_tapestry_01: (on the bottom floor) as above

Floaters:

misc_flask_01 (x2): these models have a point at the bottom instead of a flat bottom. As such, they need to be bled a little into the surface in order to look like they’re resting on a flat bottom.
misc_flask_04: as above
misc_flask_02: as above
misc_DE_glass_green_01: is floating a tiny bit on one end
Misc_Com_Pitcher_Metal_01: as above
common_shirt_01_a: need to bleed this a bit to prevent visible floating. Also, this and the pants are for ashlanders only, I suggest changing them for another.

Other:

furn_de_tapestr_02: this is only really used in Temple ints, or if the inhabitant is particularly devout.
You should familiarize yourself a bit more with the other pieces in the in_hlaalu set. You use a lot of in_hlaalu_hall_4way with the one sided walls, when you could be using far less pieces (vanilla has pieces that could replace every single wall + 4way combo. Check them out, experiment, and use them to create that top floor in a much simpler way). 
You also use double in_hlaalu_hall_128 when you could be using one piece. Same comment as above.
I can see through the wall coming down the stairs. Either change the stair piece or change the hall pieces to resolve that problem.

Overall, this is severely undercluttered. I understand that it’s an abandoned house, but it’s hard for me to determine if you have the ability to clutter sufficiently. I ask that you clutter this more (more furniture for the empty floor space, rugs perhaps, more misc items for the shelves and tables, more lights, etc.) and turn it into a lived-in house just so I can be convinced you can clutter well. Also, it would be great if you utilized some more T_D items, although that’s not strictly required for a showcase.

There are a lot of things you do well in this showcase, but the above things should be fixed before I recommend you for promotion.