Great choices! You can't really go wrong with either! The berber with a little more beige in it-last pic- will give you more options with the rest of your finishes, fixtures, and overall palette down the road. It seems to be a better balance of both warm and cool tones which makes it an ideal neutral! Best of luck with your project!

Any good carpet installer would be able to do it. Should be no more than $500.00. For reference, we typically pay around $250.00 for the stairs when they are installing the remaining portion of the house.

Are you talking about a runner for a standard straight run of stairs from one floor to another? This article https://www.rugsdoneright.com/pages/measuring-stair-runners may help. In it it says "Straight Stairs: For standard straight stairs, a 21' cut roll runner will usually suffice. The runner is installed starting at the base of the first riser, and continues up the stairs to end just under the nose of the landing on the second floor." I don't think that Ballard carries stair runners; but they do have 2'3" x 8' runners. You'd need to use 3 of them to cover a standard straight staircase.

There is only one way to fix this and that is to fully carpet the upper stairs keeping to the left where my arrow is to show where you step juts out as well as to the right where again my arrow is where again your stair juts to the right. Follow these lines to the bottom which is centered between your posts. If the carpet store was out to measure this and do the layout they would have noticed this HOPEFULLY. If you did the measuring and ordering then you are stuck with a partial redo as this is the proper way to carpet these stairs. My image is crude but you get the idea.