How to restore/replace an old wood window without losing daylight opening
YES! It is possible and likely will be rewarding as a labor of love.

You will need to become familiar with the parts and assembly of old wood windows and will learn the names and functions of the various elements as you progress in your endeavor (e.g. stool, parting bead, stile, rail, etc.). There is tons of info on the internet of things.

You will need to become proficient with stripping, scraping, sanding, painting, glazing, etc.

You will need to find a good hardware or window shop that has knowledgeable staff and are willing &amp; able to procure the parts and materials you will need (lots available online too).

You will need some specialty tools, like this "wood sash paint cutter":

 
pic from stuccohouse.blogspot.com

and various other common woodworking tools.