Guy

To Question one.
It's not weird. In fact, it's petty normal. Seen it happens many times.
But here is a catch.
What if an important person unexpectedly show up in your ceremony
(like an old friend yours who have lost contact, heard your wedding from a friend of a friend),
and you really want him/her to come to your dinner?

When you talk to your restaurant or cater on the number of meals preparing, make sure you reserve some extra plates(or seat) (about 5-10% of total guest) for backup to prevent backfire from situation like this.

It will cost little more, but save you many trouble.

TO Question two.
YES~!! you will need refreshments, not just any "drinks and food"
Not too light, not too heavy.
FOOD and DRINKs and what makes people happy and energized.

I rarely involve in wedding anymore, but PM me when you need real help.