Probably going to need a permit for a window, since you are making structural changes.
Good point. Technically, a permit is generally required even if the changes aren't structural. There are several different code sections that apply to windows, plus the exterior weather envelope is regulated, so any changes to that are also regulated.
Getting back to a question from the opening post that hasn't been discussed:
I'm hoping to not have to remove any siding planks. I have a good blade for cutting thd siding though.
I don't think it's possible, the way most windows are made today. With an old, wood window that has a real brick mould for perimeter trim, you would have cut back the siding an inch and a half (or so) beyond the rough opening, to the exact size of the outer dimensions of the trim, install the window, caulk, and be done. It's almost impossible to find a window like that today. Most have a nailing fin that's both the mounting and the flashing. The design is intended for the siding to then lap over the nailing fin. There's no
good way to do without removing or cutting back and patching the siding.
I did see a guy do it otherwise, once. The assistant pastor at the church my late wife and I attended had a second floor apartment with a habitable attic. He was renting it to a woman with a bunch of kids, and they were using the attic as a bedroom. It didn't have a legal escape/rescue window, and I was concerned that if something happened, the padre would be liable because he had allowed kids to sleep in an illegal bedroom. I bought a window at Home Depot, and a member of the congregation who is a home improvement contractor volunteered to install it. I met him at the padre's house on a Saturday morning with the window and watched him work. The first thing he did was cut the nailing fin off all four sides of the window.
"Now what are you going to do?" I asked.
"I just screw the sides to the rough opening," he said. "Simple."
"And what about flashing?"
"Ummmm ...."
So I went back to Home Depot and bought a roll of aluminum flashing stock to fabricate something to replace the fin that the idiot had just cut off. We used that on top, but on the sides he just loaded it up with caulk. Which might be okay for a year, maybe two. Once the caulk dries and shrinks, it's useless. So you need to remove siding far enough beyond the rough opening to have a place to nail the nailing fin, then you replace the siding to overlap the fin.