A large number of mortgages shouldn't hurt your score. Inquiries in the last 12 months and new accounts in the last 12 months will hurt your score,
AFAIK. The credit card ratios they use are the amount reported (the balance on your last statement) divided by the limit. Unfortunately, paying the balance in full has no effect. You can pre-pay your credit card before the statement comes out so that the balance reported is a low percentage. I've heard 5-10% of your limit generates the highest scores- higher than a zero balance. A large number of open revolving accounts can hurt your score. Also, some credit cards don't report a limit, so you get treated like you have a maxxed out account. Those credit card companies were sued, but prevailed. Those accounts should be closed if you're trying to get a really high score, or kept with zero balances. Perhaps closed if you have lots of other credit cards.
If you run your free credit report, you can pay extra to get your score. The scores they give consumers are often up to 20-30 points higher than the scores a mortgage lender will pull (FYI). When you get your score, you'll also get the four top reasons (score factors) why the score wasn't higher. The first one or two score factors carry the most weight. Even people with 800 scores will get the four score factors. It's the worst things they can say about your credit report, but it doesn't mean anything if the score is so high.