Do you earn less points if you don't make giveaways?

No.
You gain points when other people make giveaways.

LoL, you actually don't get less points. I forgot how the point system worked, but someone will eventually post the mathematics of it for you to understand.

Edit: "But if you're too lazy I'll summarize it. A dollar is worth 1 point. if you want to enter a giveaway it will cost you as many points as the game costs. So if you want to enter a giveaway for a $1 game like Fortix it will cost you 1 point to enter it. Whenever someone makes a giveaway for a game after you sign up everyone will receive 5% of how many points that game is worth. So if someone makes a giveaway for a $60 game (or 60 points). Everyone on the site will receive 5% of those 60 points which is 3 points. The maximum # of points someone can have on the site is 300 points so everyone has a fair chance."

From CG: "When a giveaway is setup, all users, excluding the creator, now receive 5% of the gift's value in points. For example, a game valued at $9.99 would give everyone 0.5 points, while a $50 gift would provide everyone with 2.5 points.
Although your points are rounded in the top navigation, they're now tracked to one decimal place."

Sources:

• http://www.steamgifts.com/forum/lalkl/point-system-now-live
• http://www.steamgifts.com/forum/Qe2b2/how-does-the-point-system-work
• http://www.steamgifts.com/forum/search/point%20system

No.

Nope :D

No, u gain points when people create a giveaway.

You get 5% of the total value in points of all the giveaways created. Being the minimun at 1

it's all explained in the FAQ =)

you get just as many as anyone else. contributor or not