>>2) It will depend on if the trend matches that equation. What is the value of the next point in your hypothetical? <<
That is what I am trying to calculate.
It was your hypothetical, if you don't know the value then who does? You need to actual to test the accuracy of the prediction...
>>As an exercise, you can use the first 4 to predict the 5th and compare it the actual 5th. The predicted value is 155,000, 18% lower than the actual. Is that close enough accuracy for you? <<
No. I would like the results to be within 5% of actual.
Then you need a different model than a linear one based on just the year. That means you probably need more variables than just the past prices and the year.
>>3) There are many different types of strategies. [Google can be your friend here, it is not an excel question, though excel can be used once you have a strategy chosen, it can do more than simple linear modeling]. <<
What phrase do you suggest I search for?
In addition to "Case-shiller" Try "forecasting home prices".