Mont St Michel

IMHO the most wonderful thing about the Mont is viewing it from a distance -- but it is also very much worth visiting and climbing up to the Abbey. One of my favorite photos is one I took of the shadow of the Abbey on the mudflats taken from the courtyard of the Abbey -- it's on my living room wall.
https://janettravels.wordpress.com/2014/01/21/mont-st-michel-is-that-a-real-place/
We were there in late October and it wasn't crowded -- I don't know about Easter Saturday but I'd guess it would be pretty crowded but nothing like mid-summer.

thank you! is this your blog? It is very helpful!

I don't know the answer to the your first question.

The second question has advocates for both options. The view of Mont St Michel from afar is iconic. Seeing its outline against the sky is, by itself, an experience worth having. But that is clearly different from going out onto the island itself. Going onto the island includes walking up the main street, the smaller and smaller stairways and passageways, and the ramparts. Going out onto the island provides a view of the Abbey and the island from a different perspective and might (if you buy a ticket) include entry to the Abbey. It could also include walking amongst crowds of fellow tourists and seeing lots of overpriced shops and restaurants. That will vary with the season and time of day. There's a fair amount of that even if you stay onshore.
They are entirely different experiences. It's up to you to decide which is preferable.