Where to by Replacement window?

I would like to install a basement window in a room that currently has no window in it. I have a few reservations about the project. I won't be doing the concrete cutting myself, but I'd like to do the rest of the work. After the concrete is cut, I know I will need some pressure treated lumber as a "frame" to attach the window to. My first concern is how to I secure the lumber to the concrete after the hole has been cut? Second concern is if the whole is cut too large what do I use to fill in the dead space? Third, what kind of sealants will I need to complete this project? Fourth, I was told that I need to use a piece of angle iron as a header to help hold up the wall above the cut. Any advice on doing this? If anyone knows of a step-by-step type tutorial on installing new windows, I'd love to have a link. Although any helps and/or suggestions will be greatly appreciated.

Im not sure if there is another name for these windows, but they are sort of like sideways casement windows. My wife likes to call them "camp windows" but I dont know if there is a correct term for them. Anyway, we are looking at windows and have gotten a few prices for Harvey vinyl double hung. All but one place quoted me a price for a replacement window, where as the last one says that because of the way these type of windows are made, a replacement window can not be user and new construction is necessary. He did say I could use replacement windows on the 2 old double hung windows in the room. Anyone know if this is true?