Tim,
Maine is a little different on their point system. Points are just extra chances in the drawing, so say you had 4 points built up (1 per year) and you bought 6 chances ($35 for a nonresident), then you actually have 10 chances in the drawing. Only one point is awarded for each year you don't get drawn and you have to put in every year for your chances to stay current. Miss a year, lose the points you have accrued.
Nonresidents do have a small advantage, though. They may purchase 10 chances for $55, and they may buy multiples of 10, so 20 for $110, 30 for $165, etc. Residents don't have this option, we're limited to 6 plus whatever points we have built up.
Lastly, points are not unit specific. The drawing is set up so if your name gets drawn, they look at the WMD's you put in for and see if remaining tags are available where you want to hunt. To better your chances, be sure to fill in all 10 choices in the order of preference. Some guides are flexible in which zones they'll guide in, if you ask.
Hope this clears it up a bit.