Having memorial wreaths at seats of our deceased family is a great idea. I was trying to think of a way we could incorporate my fiancees mom and my mom, being that they have both passed away. Would having a picture of them be too much?

Here is a tip for those of you who will have a young flower girl or ring bearer (or both).
Young children sometimes don't make it down the aisle very well on their own. Try having a family member escort them down the aisle or at least follow them to keep them on track. Also remember that 20-30 mins is a very long time for a child to stand still. Have seats ready for the children and someone willing to grab them once they have reached their limit or right after they have come down the aisle.

Carly,
I have seen the officiant ask the mothers to come to the front. The bride gave a small speech and an I love you, hug and kiss to her mother then gave her a flower. Then the groom did the same for his mother and gave her a flower to honor his mother.
For presenting the child with a gift- The children have always been a part of the service. They were either a flower girl, ring bearer or walked their mom down the aisle. Again, the officiant had the child come forward while the mom and dad either pinned them with a pin or gave them a necklace that signified their love and dedication to that child. I have also seen the biological parent give them something and also the new parent. It is similar to the relevance of the giving of rings to include the child in the new marriage. Ask your officiant if they have seen this down and ask how to involve in the ceremony. They will have great tips for you.
One more thing is the unity sand. I have seen the entire family take part in this as well. Use multi colored sand(a color for each person) and all mix it into a beautiful vase. It is to symbolize your new life together as a family.
I hope that this helps :)