I'll try to help.

My understanding is you get automatic silver status as long as you hold the MR Visa. Although if you never stay at Marriott, I am not sure silver status is worth much.

Definitely take the points if you stay. They are worth a lot more than the miles and frequently they have promos which are only good for point earners.

Finally they are giving 15K points when you get the card which is 5K more than usual. Also the fee is $30 a year but waived the first year. You get 1 Marriott point per dollar charged to the card (3 points per dollar charged at Marriott properties).