1. true, anywhere between 0 and 100 per year
2. free ones, rarer than the A850, and rarer still is a good quality stable free one. What happens is that someone publishes the line online, and any number of people who see it can put it on their machine (the more on it, the less stable it is). Usually the free ones(in my experience) are one day servers, so you ave to change your line everyday.
3. 50-100 now, inflation has been good on these things, they haven't really gone up by that much, the thing for you to do is get as many trials as possible, and find the best value line for you - measured on the reliability per price, not just the cheapest.
4. are they likely to go up - if they do, history would lead us to believe that they will go up a small bit, if it is too expensive for you, at that stage you can shop around again.
5. Hope that helps you somewhat.