I've been to two. One the dad of one of my best friends a few years ago. The other in the 1990's, a more recent veteran. But, yes, dress appropriately. Your description of your planned attire is perfectly fine and correct. Don't bother with flowers. Come back a later time if you want to leave flowers. The military handles all aspects of the funeral and there is not really a place for flowers. The 'pace' of the funeral will be quicker than what you are used to with a civilian funeral. Very rapid, orderly military precision. You won't be standing around a lot.
BTW, the 'waiting list' is likely not the family's fault. It takes months to catch up on the backlog. The scheduling of the funeral doesn't happen until the veteran has passed. And the waiting list list is very, very long these days, as WW2 veterans are passing quickly.
Sorry for your loss.... IIRC, there is a page on the Arlington web site that gives advice on dress, etc.
Sirhr