I too, will be converting a combo stock trailer into a LQ trailer. I wanted 8' wide, couldn't find one, so ended up ordering a new one. My quarters will be snug, but doable, if I plan it right.

I have had a pickup camper for 20 years, and it has taught me some things.

Refrigerator: I like having a propane/electric/12 volt model but the 12 volt option is becoming obsolete. In 12v mode, the refrigerator does draw a lot of power so the only time I used it was on the road to keep stuff cold. I would not want an all electric refer as power is not always available. As an FYI, if you get a used propane model, they usually need either replacing or rebuilding at about 10 years of age... depending on the care people have taken of it. (They should not be run when not level or it gives the "pipes" cholesterol.)  I plan on approaching the local refrigerator repair shop to see if they have a reconditioned one in good shape instead of buying new.

Also, Tupperware ice cube trays with lids are wonderful in LQ set ups. They don't leak if the ice happens to melt. And the ice stays untainted by any odors in the refer. 

I have found that most times, I don't have electrical hookups where I go. And, I have not had a lot of good luck using a microwave powered by a generator. I fried two before I gave up trying. I'm wondering if it was the fault of the wiring set up in my camper, even though the camper was set up to contain a microwave. I won't bother putting one in my new trailer/living quarters.

Flooring:  It is hard to keep a smooth floor free of debris and carpet is out of the question as it is too hard to keep clean. I use wall to wall scatter rugs on the floor that I can take outside and shake out while away from home. It is just easier to keep the dirt out of the bed and bathroom/shower that way. It seems I always have kids running in and out, or, adults in barn boots or deep treaded tennie runners.

Now to figure out how I can take my Big Green Egg (barbecue) that I love to cook and eat from. (They do make a mini!)

IMHO...I would forgo a microwave unless you have atleast a 3000 generator. We have one in our LQ and use it for storage..it holds bread, chips, tortillas, etc very nicely.

Looking forward to updates on your conversion.

Yes, the retractable steps come in many widths and sizes.

We have a dinette that converts to a bed...it connects to an L shaped two seat couch...I am 5'3" and it is tight for me. I would go with the couch as long as you have the fold out room. When closed, you can put up a table.