Answer to the first three questions is unequivocal YES! In re front squats, core seems to be the most taxed part.
And I am looking forward to double swings!
I've only done double 24s myself. They were a nice weight but ultimately too light for my tastes. Had I bought myself a second 32, I believe I'd have been content in my programming for longer. I did a lot of front squats and presses with them. I didn't really like the cleans as the stance had to be so wide but it may be a question of habit. It will be interesting to see how you like the swings. I think 28 cleans with those double bells is a nice bit of exercise in itself.
How long did that last workout take? That's a lot of sets.
There are A-(squat, press) and B-(swing) days. A-30 minutes, B-20 minutes, and this is the same for the whole 12 weeks.
Is blindness a symptom of overtraining? Maybe I should take a rest day. I didn't really sleep well at all last night.
Do you do one set at a minute or how do you regulate how long the sets take?
Training like that is dangerously close to cardio. One might almost get a sweat.
2*32kg to forehead height? Impressive strength. Have you tried 2*40kg to hip height?
I agree with @Antti, those kind of swings are really hard! If you can manage to swing continuously to that height I think you are ready for double snatches with them. I think that I could do a few of those swings and maybe a snatch, but doing this for multiple sets is out of my league now. You are Strong @Mirek!