Edwin, If I were you, I'd talk to your doctor about the Pred situation. And, if it were me, I'd rather toxify my body with a "preferred" generic!
Mestinon doesn't "build up." It has a very short life. It kicks in after about 15 - 30 minutes and then wears off about 2 hours after that. You might need to take it more often or take a higher dose. DO NOT change things without talking to your neuro first. More isn't always better with Mestinon. It can make you weaker if you get too much of it.
I would need to write an anthology to explain the possible side effects of Prednisone/steroids. You can have mild to severe effects, some that last a long time. You can have Pred-induced diabetes, brittle bones, increase in infections, digestive issues such as a leaky gut that can lead to more immune problems and so on.
You definitely need to be on a calcium and vitamin D3 regimen. Plus some good omega 3's.
Ptosis can be impossible to get rid of, even for people on all sorts of drugs. Mine fluctuates greatly during the day, though I'm only on Mestinon.
If you have eyelid surgery, you will still have muscles around your eyes that will get weak and "droop." Then you'll look like people who've had too many facelifts! It's a personal choice but you need to know that surgery is not necessarily the answer. Talk to your neurologist about it too, for a second opinion.
I've had eye appts. for years with Mestinon and without. You can only deal with the current state of how you're doing right now. The eye doctors can figure out what your vision, whether you have ptosis on the day of the exam or not. Also, the drops they give you for the exam can make your ptosis and MG worse! So it really doesn't make sense to wait.
Does that help? I think you need to have a sit down with your neurologist. Write down any questions ahead of time and maybe even give him a simple list of them. It can be easier and quicker for doctors to read your questions than to have you say them.
I know this is a hard thing to go through. When I first knew I had MG, I read every single little thing I could get my hands on. While the medical books, articles, PubMed and the Internet were great, it was the people with MG who helped the most. Just give yourself time to adjust to it all. And keep on asking questions!

Annie