The only difference between buying from Marriott versus resale is that you cannot trade your unit in for points (limited to once every two years) if you purchase resale.

You should immediately go to www.tug2.net, the site of the
Timeshare Users Group. There is a wealth of info for you there. There is a menu link (on the left side) for Advice. Look there and you will find lots of information. Specific questions can be answered on the bulletin board.

You will find that most people on FlyerTalk are not interested in timeshares.