Hi Dave,
dont worry, we all have moments like this. I have done exactly the same as you, I took and old alarm clock apart and then couldnt remember how to get it back together. Over the space of two years I must have got that clock out 5 times and tried again but each time I just didnt have an idea and would just put it away again. Then a month ago I got it out and it almost fell back together on its own. Its experience! No matter how much money you spend, books you read, videos you watch there will be times when you jut cant get your head around something. Take my advice, put it away and try again in a couple of months. If you are desperate to get it back together then take some pictures and post them up, someone here will be able to help you.
As for demagnetising that screw, have you tried putting it into one of those small zip bags and passing it through the demagnetizer? Also the end of your screwdriver.
Watches can be very frustrating because of the small parts involoved. First of all make sure you have a good eyepiece or loupe, I use a 3x loupe for my clock work but find I start to struggle with watch stuff, I need a stronger one. Then it is just down to pratice. If you ever feel you are getting frustrated with the watch just put it down and walk away, take a breather. We all go through it, dont for a second think that we dont.
Dont give up Dave, you will get there and we are here to help whenever you need it.
Paul 
