Lots of questions guys:

1) can a member choose to break down their payments monthly instead of all at once? Our yearly membership dues are roughly $1500-$2000/yr.

2) does the payment history show in their profile automatically?

3) is the payment data available easily in the database so I can retrieve it to show them what they have "donated" that year in a module?

4) Plans to be compatible with Joomla 1.6?

so for question #1, I'd have to make a 2nd Plan for the monthly payments? Wouldn't it make sense for users to select their plan, add their donations, and then select whether or not they want to pay in one lump sum or in monthly payments?

The reason I ask is that our members will have Plans that are anywhere from $500-$1500. On top of that we ask for another $250 for DonationA and $500 for DonationB. I really can't set up a different plan for each possible scenario of each of those if they want to pay monthly.

I guess if it's not possible now, I'd like to make a "formal" feature request.

It'd look like this:
"You have chosen Plan B @ $1500 + $250 + $500 for a total of $2250. Would you like to pay in one lump sum of $2250 or in 12 monthly payments of $187.50?