Okay, I tried moving an existing chair, and it didn't work. So here's an easy non-CK method to add a comfy chair to Lydia's room:

1. Stand to the left of the end table in Lydia's room and face the door.
2. Open the console and enter player.placeatme c2a01 1
3. This'll bump you towards the door, so turn around and see the fancy new chair.
4. In the console, click on the chair, then enter the following two lines: setpos x -830 and setpos y 340

That should do it. If the chair spawns tilted one way or another, click on it in the console and use getangle x (x being the usual suspect axis) and if it isn't zero, use the complimentary setangle x 0. This won't do anything by itself, so follow with a setpos command and it should pop into place.

Hope this helps!

Tip for your next character: Leave Lydia at home if you decide to climb those steps next time at a low level. And get the Wabbajack as early as possible, then blast her with it every 10 levels or so (up to 50, her cap) until she transforms. That will bring her up to your level after she becomes human again. I think you need to release her from your service beforehand, then tell her to follow you again after. Lydia is actually a good fighter for you if she's near your level.

Oh dear! So Lydia may still be hanging around that mountain! I'll have to go look soon since I'm doing a quest in the region, need to finish that first since I have some guy following me there. What lvl is that troll on the Thousand Steps anyway? I'm now lvl 24, so that is 10+ lvls over last time I was there. I assume fire is the best way to kill it? Any advice welcome as I feel something of a vendetta against that thing!


And what, pray tell, is a Wabbajack?

It's a Daedric quest reward staff that produces "unpredictable results". You get it from http://elderscrolls.wikia.com/wiki/The_Mind_of_Madness quest in Solitude. You'll want to save every time before you use it on a follower because it can cast offensive spells. The effect you're hoping for is one that transforms the follower into a mudcrab or rabbit or fox or something like that. Then when they recover they'll be 'reset' to your level up to their max (housecarls are all 50). The follower should not be 'following' you when you use it.

That brings up the question of what level is a follower? Are they the same level as you when they first follow you, or when you first meet them or interact with them? I've switched followers several times, and have met several others that I've interacted with but not had follow me. What level will they be when I do ask them to follow me?

And then, if their level is lower since first follow, or first met, I guess when I'm ready to have them follow me I want to hit them with the Wabajack and have them follow when they're human again? Then repeat every 10 levels?

Their level is set when you enter their cell.

Wabbajack them when you feel you've leveled past or too far past them.

This might be useful too:
http://www.uesp.net/wiki/Skyrim:Followers

"Just to be thorough, I did purchase the bedroom suite so my bed doesn't say owned. This little bedroll was there from the day I bought it when I did my "home inspection"! LOL In other words, it came with the place."

As an aside, when you bought Breezehome, you bought it from under Lydia's ownership. No wonder she gives you the looks she does early on in your relationship.

Treat her well.

She lives in Dragonreach before she's assigned as your Housecarl.