Refinishing your floors to match will require an expert to come in and access them and determine the finish on the other flooring. It can be done but sometimes without 100% success.

The mess is negligible and undo-able, the smell - will be a few days, best done when windows can be opened and the weather is on your side (dampness extends drying time). Normally they run large fans to dry the floor. Downtime is several days after the last application but care must be taken until the floor cures which takes about 1 month.

To prep for this all the furniture needs to be moved from the area. My floor guy hangs wet material to reduce the dust entering other rooms. It's noisy and I normally plan to leave the home for 2 or 3 days while the floors are done.

In one home I owned, I had an issue when the old carpet was lifted, the previous owners pet left dark demarcations. That floor had to be stained darker then I wanted. To compensate and give a better transition between rooms they masked off a border design and matched that border to the lighter stain. The floor came out beautiful.

The sanding creates a ton of dust, which gets into everything, so try and seal off doorways with plastic taped to the frames, to reduce the spread to rest of house. I don't remember the smell being too offensive. But once floors are stained, I believe you can't walk on them for 12-24 hours (someone can advise you exactly).

The most common/professional way of going about a "floor match" is to A) find the right species and plank width and then B) install the new floor. Once the unfinished wood is in place the ENTIRE FLOOR is sanded (old and new alike) to expose/create a continuous floor. Once all the floors are 'raw', then a finish is applied (stain if you wish...natural if you don't) and then you have 25 years of life in the finish!!!

If the existing hardwood is "old" then it is probably time for it to receive a full sand/refinish anyways. This is needed every 20-25 years...which means you may be ahead of the curve by a few years...maybe not.

Once the floors are finished, you will need to stay off of them for a few days (a week sometimes) and then you need to be "careful" (no shoes, no dragging things around, etc) until the full cure has been achieved.

It is best if you are out of the house during this event...but you want to be "close enough" to be able to inspect the floor at every step/stage. Don't go "out of town"...but perhaps you can splurge and give yourself a Weekend Away at one of the better hotels in the area...you want to be an easy distance away because a homeowner is expected/encouraged to approve each stage as it goes along. A visit every day is well worth it in the end.