[John Smith_]

I would use the black plastic plate to center it all up.
And, welcome to the forum !!

 

[John Smith_]

the table is press board. Do you guys recommend adding a lacquer or polyurethane coat to the exposed wood to seal it?
Thanks.

For me, I strongly recommend it. When I work with "press board" or similar, that is the first thing I do is seal it both sides. In florida, just one week can make it swell from the humidity. Come back and show us your setup when you get it fine-tuned.