If you are going to do it yourself then that is one thing, but if you are going to hire pros that is another. If you are going to hire pros, the 1st thing to do is call each one, a window, a roof and a siding pro and get some estimates on the cost. Add the repairs to the price of the house and do a dollars and sense thing to see if it makes sense.
If you are doing it yourself then you have a lot of work ahead of you but you know that going in.
You can replace windows yourself at about 25% of the cost a pro will charge. You can do the roof yourself at about 25% of the cost of pros, in fact everything you seem to have to do is very labor intensive and not that material intensive. Wood peckers just made holes in the wood, it doesn't mean they are insect damaged.