Welcome to the site,
I would not wory about the serial number as Stevens 200 rifles was only made for a short time. Starting around 2004 with a late change over to centerfeed magazine system in about 2007 and this year is rumered to be the last year of production.

Yes, removing the actions srews is all that is needed to remove the action. Removing the rear trigger guard screw is not needed, as all it does is hold the trigger guard to the stock. If you have a stagared feed action, when you remove the action from the stock you will have a magazine spring/follower fallout of the action as it is held in place by the stock. A centerfeed action the magazine will stay comnected to the stock.

Yes the two small crew holes in the rear of the recoil pad can be removed and the recoil pad will come off, but there is no need to do so.

Many question can be asnwered by using the search feature, and the FAQs section,
enjoy.