Cruising Kwong

Hey everyone, new cruiser here. I went to the casino and got 1200 points on my 1st cruise in december and got a free cruise offer. After that I got a few more offers, is it because I got 400, 800, then 1200? Do I get a free cruise offer every level? I know at 1200 I get a balcony cruise instead of interior only. If anyone got prime, is it worth it to gamble more to get 1300 more points? Does that mean I get free drinks when gambling? Also can someone tell me about what happens when points reset in March? If i'm not prime it resets to 0 and I have to start over again?!