Thank you so much, guys! (And pics help immensely

thank you )
We already bought the bath exhaust fan so it'll be a matter of getting a warm spell so I can tolerate working in the attic. Lol But, Gary, should I just end the exhaust venting at the end of the roof rafters and not hook it up to anything?
I DID finally crawl up into the top attic to see what I could see. What I found that I believe to be part of the problem was this: No true gable vents, but make-shift "doors" that worked using a pull string (attached to a spring) through the window framing to open and close. It looks like there had been angled slats there at one point, but they've been removed for the most part. The "door" in the vent above my daughter's room worked more like a hatch door than a regular door like in my son's room. So...on cold windy days, the hatch "door" - when opened - would direct the air flow down the wall directly over the windows...WHERE THERE WAS NO INSULATION IN THE STUD CAVITIES in the 3 above the window!!! Holy crap, I was pissed! Lol I hate having to shove insulation in where there's tons of nail sticking out, but I came out virtually unscathed...thankfully.

My back wouldn't agree so much...cape cod attics are not forgiving for taller people. Anyway, I put insulation in vertically all the way down to the window framing and then put an extra piece in horizontally at the top. This has made a HUGE difference, but if I pull back the shrink wrap on the windows, it still feels like I've got a window open...and the hatch "door" vent is closed until I go get REAL gable vents. So, without taking the window fully out, I'm not sure where that sizable draft is coming from.
Second issue...neither interior wall of my kids' rooms that create the stairwell have top plates on them. That would explain why that wall felt almost as cold as the walls along the attic. Whoever had put extra insulation up there didn't bother putting any in my daughter's wall (since it's only about an inch gap) and they just laid sections of batts across the top of my son's wall...which is about 4"-5" gap. I just put shoved some insulation in there too for the time being.
The good news...all the 2nd floor wiring is easily accessible from the top attic so now, I can replace all the old cloth-covered wire with new and not have to worry too much about fishing!!

Sadly, not having the top plates on the walls make this a lot easier also!!
Gary, nealtw, and old/new...you have been a TREMENDOUS help!! I have scoured the internet and so many people with cape cod issues and not a lot of answers. I'm thrilled I found this forum!
I'm going to leave this thread active (if I can) as I KNOW I am going to come across an issue and not be sure how to fix it.
Thanks again!!