Regarding the guide, a few more illustrations would help to break up the long paragraphs. And if you have a friend that is a professional writer (newspaper editor, book editor, etc.), they could help clean up the presentation for you. What you have is a good first draft.
As far as the rest of this goes, even though you haven't asked for it, I'm going to give you an opinion:
As I've mentioned before, there are a lot of grey-beards on this site that that have more pinball knowledge in their little finger than the rest of the folks on this site combined (no offense intended towards anyone in this forum). They are a wonderful resource for everyone and an asset to the pinball community. To tell them they are old and dumb might be short-sighted, and is without a doubt disrespectful. If you were to consider a different approach, you might get further ahead, while gaining a lot of respect on this forum, which is something I think is important to you. Just look at how most of those guys conduct themselves here. They aren't the ones getting into these flame wars. They don't need to.
I think that you are getting bashed a little bit more than you should be for the donation request that you made, but by the way you have handled it, you make for easy fodder. The only reason that any of us would ever ask for our money back is because we've felt disrespected by you. I've got an idea that could turn things around for you quickly, and nobody would ever give you grief ever again about that money:
Take everything that was donated to you, buy the best pinball machine that you can get for that amount of money, and take it up to a local boys/girls club, or youth rec center. Maintain the machine for them. If you get a couple of kids that seem to really take an interest, you could take some time once a week and show them how a pinball machine works.
This would give the kids a fun after-school thing to do, it would be promoting pinball to the next generation, and you might get one or two kids that develop the same passion for pinball that you have. There is nothing more rewarding than getting someone else excited about a hobby that you love. And make sure to either set the game up on free play, or if you are going to have them drop quarters, donate all of that to the rec center.
Which brings me full-circle back to the grey-beards. See how the circle works?
When you sit on this site and lash out, say horrible things about parts companies that may be a little unfounded, make lousy comments about some guys wives, or post pictures from Allentown where an older fella may have had a small accident (trust me, when you get older, you will figure out that wearing darker pants is a good idea), you don't present yourself in a very positive way. The high road will get you to where you want to be in life lot faster, and with a lot less grief.
Maybe that's just who you are. Or maybe you are just trying too hard to make a place for yourself in the pinball community. Instead of telling everyone how great you are, put your head down, keep your nose to the grindstone, use your ears more than your mouth, and let other people figure out how great you are. It means a lot more when you earn people's respect from your actions, rather than trying to force it down their throats by telling them the great things you have done.
Just a friendly opinion from a grey-beard that has gone through similar growing pains in a different industry. Best of luck to you going forward.