Thanks for the comment. This isn't necessarily going to be completely diy. I do anticipate hiring a structural engineer to analyze the foundation and the size of the window vs need for structural support. It is going to be a rather long process but I am ok with that.
I am going to put up studs/framing. I debated fitting it out vs all inclusive products and I decided it would be easier and effective to just frame in the space.
What's the best thing to do to prevent basement leak?
Make sure your grading is properly sloped away from the house, your downspouts are positioned properly, and your sump pumps are in good working order. Unless you have a really high water table, if you keep the water away from the outsides of your basement walls, it won't want to come inside.