On the trim... Your trim relay for the raise position probably needs to be replaced. To check this, simply swap the raise and lower wire harnesses at the trim relays and try again. If the motor raises, but not lowers, that is your problem. The relays are fairly cheap and can be found at auto parts stores and are about $10 each. If you find that to be your problem, don't cheap out and replace both. My last boat would go through one about every other year.
No spark... Check this link. http://forums.iboats.com/showthread...125&page=1
The first thing I would check is the kill switch, neutral switch and the chassis ground at the motor before starting to replace parts. The kill switch or neutral switch are often overlooked and can make you feel really dumb when they get out of adjustment.
Be sure not to change the polarity of the battery. Are there any electronics such as fish finders, radios, etc hooked up to the battery? I'm no expert, but they probably don't like the reverse polarity and you may burn them out or cause damage if you keep doing that. This may have caused your problems with no spark also.
Good luck troubleshooting!