Okay, since I do need to understand this better I decided to do a little research on my own instead of just letting everyone do my research for me.
First off here is a link to the wikipedia article about the assumption of Mary:
en.wikipedia.org/wiki/Assumption_of_Mary
And then I found this site:
ewtn.com/library/answers/aofmary.htm
Which states:
At the Council of Chalcedon in 451, when bishops from throughout the Mediterranean world gathered in Constantinople, Emperor Marcian asked the Patriarch of Jerusalem to bring the relics of Mary to Constantinople to be enshrined in the capitol. The patriarch explained to the emperor that there were no relics of Mary in Jerusalem, that “Mary had died in the presence of the apostles; but her tomb, when opened later . . . was found empty and so the apostles concluded that the body was taken up into heaven.”
Which I, personally, found interesting.
As to the Coronation of Mary.
First the wikipedia article:
en.wikipedia.org/wiki/Coronation_of_the_Virgin
which cites these biblical passages as support:
Song of Songs (4.8), Psalms (44.11-12) and Revelation (12.1-7).
There is some interesting information on this site:
campus.udayton.edu/mary/resources/crowning.html
This is an anti-Catholic site that has some objections of Mary’s coronation that you might actually find helpful:
jesus-is-lord.com/mary.htm
If you know the objections it’s easier to combat them right?
Anyway, that’s what I could find. The Assumption is easier to find information on then the Coronation… and these are just a few links from a google search but it’s what I’ve unearthed.