Since for me 13.1 miles is a really long run, would running the course Sunday morning be a problem for Running the Friday morning marathon?
I know that it is not a big deal because i will have most of the week to recover but ideally in a perfect scenario would one do it?
Any Suggestions, Comments and Answers... Please
In a ideal scenario I would not do it. You could also do it with a bike (which would make it ideal

).
I'd also like to hear advices about long running sessions. I'm getting ready for my first marathon this spring.
The only suggestion I have is that you should definitely run the course before the actual event because you'd be psychologically prepared for the perils on the road.
Knowing the track is unnecessary. Only if you want to win and you have other world class athletes starting as well. Than it could help to know the track but still it is not necessary. Or the are very special features on the track (e.g. steep ramps). Or if the weather does not fit the track (cross county runs).
If you are mega nervous it could help to know the track if it is relaxing you - if it is not calming, it is unnecessary

.
In general it is much more important to know yourself and your capabilities and limits. Then the track does not matter that much... You only need to be prepared for special tracks... if there is a e.g. a steep ramp (e.g. 10% incline) over a longer distance you should know it so you are prepared when something hard is facing you. Or if you are pro where to place your attacks

(but often your and the competitors fatigue are much more important). But that does not equal knowing the complete track.