Membership rules question - can I prorate and use date based rules?

With the Membership plugin - I'm hoping to use it to manage membership of a Mom's club. Our current membership rules are based on some dates.

The first one is that all membership dues are due at the beginning of the fiscal year, so I'm wondering if there is a way to have all memberships end as of August 30th and renew on Sept. 1, and prorate dues if they join after a certain date? (This would also work for PTA, for example, in which dues are based on the school year).

The next question is that there are different membership levels based on the age of their children - is there a way to take a date from their profile (the age of their child) and let them know the membership they are eligible for? (basically, they get a reduced membership if their kids are 4 years or older because they become less involved as their kids get more involved in other activities).