Its not the OP who will see legal issues...its the modular company who had their architect sign off on the plans that will get sued in the end. Even in Yankee Barn attempts to go after the OP, the OP can turn around and go after the modular company. Since it sounded like OP was already planning to change the plans and was in the early stages I doubt Yankee Barn would go after OP. At this point either the plans were changed heavily or OP could hire a contractor to finish off the inside of the house and avoid showing the town building department as much as possible. I doubt Yankee Barns legal team would waste funds to take someone to court over an online discussion board. If OP had to pay for plans in the first place...its highly likely that the modular company contacted Yankee Barns architect and bought them. Its 2018 and with websites like this i doubt a modular company would risk it.

Carpet is probably the cheapest option. There will be a lot of labor to prepare the steps for another type of flooring and install it. The overhangs will have to be cut off. Make sure that your flooring choice has matching nosings and consider what you want on the risers. The old carpet lasted 16 years. Get a nice looking low nap carpet and be done with it.

OK...Here are some suggestions. If you KNOW the tile is coming out in the next 5-7 years (I call this the 7 year renovation time line....which you plan out EXTENSIVELY before you TOUCH a single surface...right?) I HIGHLY recommend you put in a SOLID hardwood upstairs. You will have it SITE FINISHED to the colour you want for then next 25 years. Leave the stairs alone for now. Recarpet if you must...but leave them alone. You will choose a REGULAR 3.75" narrow strip hardwood in a regular wood (Maple, Red Oak, White Oak...nothing crazy or exotic). You will do this with the FULL KNOWLEDGE you will *most likely run this through the MAIN LEVEL at some other point in time. You want to be able to source the product in 7-10 years time...so you can have a consistent WOOD throughout the home. You do NOT have to have the same COLOUR on the two levels but you really want to try to keep the same SPECIES, WIDTH, and CUT for future renovations/refinishings. You will 'match' or 'compliment' the stairs to the MAIN LEVEL flooring (not the upstairs flooring). And THAT'S why you leave the stairs until you refinish the DOWNSTAIRS. Believe me, you have a lot of PLANNING to do for the next 5-7 years worth of RENOVATIONS. You will want to have a "story board" of colours that you want the ENTIRE HOUSE to be draped in BEFORE you touch the flooring. We've seen FAR TOO MANY PEOPLE rip up flooring 'at the beginning' (because the house is empty and it is the 'easiest' time to do it) only to have HUGE regrets that they rushed the decision. It is an EXPANSIVE and EXTENSIVE mistake to make. And please be aware the carpet is hiding HORRIBLE subfloors. I mean EXPENSIVE TO FIX. I always tell my clients to budget $2-$4/sf for the subfloors under the carpets. The average is around $2.50 - $3/sf...but a $4/sf repair is not rare. The $5-$6/sf repair/rebuild is rare....but not unheard of. Give yourself a TOTAL budget and work BACKWARDS to your 'wood purchase' budget. You might just find the 'purchase budget' is TOO LOW to get a wood floor installed.

That is a truly beautiful and elegant kitchen. i can see why you'd want to replace the backsplash. I think you'd tire less of the lighter tile in the long run. For starters on the lighting, I'd check anything by Visual Comfort & Co from Circa Lighting. The light quality from those lights is superb. Also take a look at the modern designs from Hinkley Lighting. On your floor, you might consider a product like Loba's 2K Invisible Protect or Loba 2K Supra A.T. without a stain. White oak in lighter tones is very popular right now without any stain. Here's a video showing how Loba products prevent tannin pull in white oak when applied correctly: https://www.youtube.com/watch?v=Kbu7kCzd1P0