Hello teenyuck:
I am a Catholic and have been for eight years; I joined as an adult in 1994.
The pre-wedding waiting period is a common practice with a usual length of six months. The main intent for this tradition is to provide the participants with the opportunity to demonstrate their sincerity and mutual commitment. A secondary goal is to ensure via the instruction program that the couple is fully aware of the spiritual aspects of marriage including the lifelong nature of the marriage bond and also the responsibilities involved with raising children in the faith.
The waiting period is sometimes considerably shortened for older couples.
In general, a divorce from a prior marriage is not an impediment if the marriage was never sanctioned by the Church.
I have never heard of any parish "requiring" a percentage donation.
For more information about Catholic doctrine and practice, see the http://www.ewtn.com site.