I am going to preface this with a lot of the work you are discussing may require permits and/or inspection . . . whether you comply with that requirement is your call.
I had a few jobs building up as things we'd like to do in our home, and hearing a breaker arcing in my electrical panel was a good catalyst to try and get someone in to take a look. The main tasks are:
Replace electrical panel and service entrance. I've got a separate quote of $2700 to do this, and I'm inclined to just pay it and minimize the time out of power.
It sounds like from the discussion in this thread the service entrance will be contracted out for time and safety purposes. You could still replace the main panel yourself. In your current configuration the utility would have to disconnect you while the work was being done and reconnect you, they may have rules about who can do the work or want an inspection before they will turn the power back on.
I mentioned in your current configuration because if you are going to be replacing the main panel anyways, I have a suggestion; have the service disconnect (which is usually a 200 amp breaker at the top of the box) located in a separate box upstream. In my house there is a manual generate transfer switch which also serves as a disconnect and it is quite nice to have the main panel complete cold when you are working in it and it seems you will be in there alot.
Replace all the knob and tube circuits in the house, which is about half of them. I can add this on to the previous for about $11k total. I'm about 50/50 on this one. I can pull wire, I can install breakers, but I'm still a little leery. Any amateurs want to reassure me that it's not too bad?
Electrical work is pretty basic, the code for designing a new space can be infuriating. But, running new wire is not mentally taxing work . . . it just involves cramped spaces and awkward positions that often result in soreness.
Replace several old windows. I've watched some videos, done some reading, and feel like this is very doable but time consuming. I'm assuming the first window takes twice as long as I plan, and by the end I can just knock them out.
Why? If they are in decent condition you should do some research, an old wood single pane window is just under R-1, the fancy modern windows are R-3 to 5 (an uninsulated wall probably has a higher R-value than a fancy window). A similar jump in efficiency can be made by building or buying storm window inserts. If you have to replace the windows anyway, yes get good energy saving windows; but, if your windows are in good condition you will probably never recover the investment to replace them.
One problematic window. I had wanted to saw cut some basement concrete to make an existing window into a larger egress window. Looks to cost about $6k on its own, but the special tools and know how lead me to think it might be beyond DIY level. I guess I'll probably just punt on this.
6k seems steep depending on what is involved and it is very steep if it is not necessary (code requires a means of egress if there is bedroom there and maybe some other conditions). In any case seek another opinion.
All the interior patching and painting associated with the previous portions, plus exterior painting. Minor siding repair as well. I can handle this part for sure.
Simply to do, but a real pain.
Blowing insulation into the walls. Don't have a separate price quote on this. Anyone have experience on whether this is a DIY thing, or to just hire it out? Special equipment needed?
This is relatively simple and should be done before painting. My FIL did this to an old farm house when he was in his 70s. If you buy a certain amount of blow insulations most big box store will give you a day or two with the machine free. Filling the attic is easy you'll just spread it out like water from a garden hose and in wall cavities you will have to punch holes in the wall to feed the hose in and blow the insulation into the cavities (hence why you do it before painting). They also make a mesh you can attached to places like the underside of exposed floor joists and then blow insulation behind the mesh. Oh and it really is a two man/woman job; one to run the hose and one to feed bales of insulation into the machine.
Overall I'm sort of in shock. It literally came in twice as much as I guessed, and I'm just going to have to find another way to do this.
Long ago I was given a rule of thumb that seems to hold true; whatever you think it is going to take double the cost and triple the time and you will be close.