Olaf does not use the FP/Return Ticket system, so it's best to get there early. When I was there in late March (just before the peak of Spring Break started), you were issued a pager that let you roam around the Snow Play area or Hollywoodland from Playhouse Disney to the Aladdin Theater. If you get there early enough, they just hand you a pager, but if you get there later, you will have to wait in line to get the pager. I got there about 15 minutes after opening and they were handing out pagers. It was about a 30 to 45 minutes wait for the pager to go off, but you don't have to go back right away (any time after the pager goes off is fine). By the time we finished seeing Olaf and looking around the snow area, it was about 90 minutes after the park opened and the sight said the wait for a pager was about one hour. So, I would try to get there early to cut on down on the wait. It is worth noting that Olaf's Snow Fest's last day is April 30th (looks like you'll be there for a few days before May 1)...no one has said where Olaf will be after that (or what system will be used).
A&E use a Return Ticket system. You put in your park ticket and will be issued a Return Ticket time window when you can come back to see A&E. You have to return within that time window. All reports so far indicate that the FP/Return Ticket for A&E is
not linked to the rest of the DCA FP system.
If you really want to make use of your
Disneyland MM, you can do that, but I would try to get back to DCA within the first 30 minutes of it's opening time to get an Olaf pager with minimal wait and an A&E Return Ticket. I would go to Olaf first, get the pager, and then go get the A&E Return Ticket.