Is alcohol allowed? When's the best time to arrive to get a picnic table?

There is no alcohol but as long as it's concealed and no one acts out of pocket and police aren't called. You should be fine.

I know that no glass containers are allowed. I would imagine if it's concealed no one will know any different. As far as for picnic tables, you need to get there before 10 or 11 or they will all be taken.