Can I use cottage cheese instead of cream cheese when making a cheesecake?
I've made cheesecake with many different types of cheese and it pretty much always worked. 

Of course texture and taste vary, but that's the beauty of it. Try a single cheese, see what it gives and then start experimenting mixing them.

For instance cottage cheese tends to give a slightly more "crumbly" texture. To compact it you can add some fresh cream. 

Sour cream also makes a wonderful addition, and marries well with some lemon zest, taken that you like a bit of acidity in your cake.

I've also tried to add mascarpone and even gorgonzola, they all work well, and give you very peculiar mouth-feelings to combine and mix as you please, but obviously add in calory content quite a bit...

As for the amount, you an just keep the same as cream cheese.