Off course it´s possible, however if you are getting into it be prepared to loose money at first. You will hear that from many affiliates...with adwords...no pain no gain.
Through good testing its possible to reap high rewards through using adwords with clickbank products.
You've got to pay attention to detail if you're ploughing money into adwords. You've got to be thinking about ctr, cpc, quality score of your landing page, effectivenes of your landing page to convert visitors to customers all the while trying not to go broke. It can be a painfull journey, but get it right and you almost have an automated money machine.
You will get burnt if you don't know what you are doing. Go into PPC with your eyes wide open. You MUST know grasps all the basics first like learning to write good ads, create specific landing pages for specific keywords and be confident of the product you are promoting. No point using unfocused keywords in all one ad group, pick a random product, set up a high daily limit with high bids and hoping that money will fall from the sky. Adwords just doesn't work that way and you would probably give up and go away telling people that Adwords doesn't work. I repeat: You MUST grasps the basics first. Hope this helps.
Yes, it is possible to make money using google adwords if you do it right way otherwise you lost lot of money. So be careful.
Yes, I spend $25 a day and profit of around $ 20 a day ..you need to pick up a niche product and niche keywords
Yes you can. But you will lose money first. You should take the advice of the others and learn the basics first, such as quality score, budgeting, CPC (cost per click) Monthly budgeting (based on a daily rate), the content network and it's contextual based ads, relevance and how it relates to your quality score (and more importantly how your quality score, amoungst other factors, can help to reduce your cost per click) Search Network advertising, parter sites, Ad Writting, Ad tracking of competitors (very important), and more... That's all that I can think of off the top of my head but there's much more to learn as well... Good Luck!