Window upgrade questions
The pictures you added, were edited with info to help you decide which way you want to go.




There are 3 options to choose

1) Out right replacement of the whole window sash and all. 


This is the most expensive way to go about it.
Its benefits are the ability to check the condition of the framing. Windows leak over time and unseen damage will be hidden.
The other considerations are you may need to remove your siding and reset some of it to get you new windows in with their preapplied trim in place. Then again, it is a newer style of window versus sash weights, and the trim or nailing flange will fit very nicely. There is a chance you will need finish it off by covering it with a PVC brick mold.


2) Renovation kit with sash and jamb. These fit a new jamb with sash directly into the existing jamb, saving the existing trim and labor removing the jamb and trim. You only need to remove the sash and track.


I have seen wood sash versions of this, but I can only find vinyl kits for an example for now.
This is a cheaper and simpler way to replace windows.
You really need to make sure the wood that is to remain is not rotted, or has taken on water at any time. This will be your only time to get this in check until you find the rot the hard way, or until the windows are replaced again.
The outside stop, if all other wood is in good order will need to be covered in metal to keep the wood protected. At that time you may choose to have it all rewrapped to inspect and cover it all without extra seams/joints.


3) Use a jamb reliner kit


Cheapest of all options
Needs to meet all of the requirements for option 2