1. Acer's are known to have heating issues, however, they are improving, especially now that they have redesigned their cooling features to support the new core i line of chips.
2. It depends on your toleration of how it looks. Some people think that some games look decent in non-native resolutions, i.e. "upconverted" to a higher resolution.
3. With an i3 and the graphics card, I don't think that you'll see much difference in terms of performance. However, check this link out to get a better idea: http://www.notebookcheck.net/Mobile-Processors-Benchmarklist.2436.0.html