In Google Adwords, what is ‘AR$’

You asked a lot of questions, I will do my best to answer each one:

1. Adwords is worth the money if you can quantify your entire costs (including obviously the campaign) and the value of the new customer. This may seem easy at first, but there are likely to be several factors in determining these values. (sorry there is no easy answer here)
2. There is a way to limit your campaigns - both by individual bid amount (per click) and you will be notified when you balance is low so you can make sure your credit card is not charged.
3. Yes: the analytics provided are robust, all keywords are tracked. You can also filter, sort and analyze a few hours away if you have enough keywords :)

Overall, I would suggest finding a free Adwords code. Try searching on twitter. You can generally get about $100 to try it out -- by then you should be pretty comfortable with the system and how to bid effectively (i.e. do not pay suggested price!)

Good Luck

1. Go to Google AdWords
2. Create new Campaign
3. and you'll find all the answers to your questions

You don't have to start paying to see how much it will cost.