With nitrous.io, you will be able to do everything you list. With an installation of chrouton, you can do anything you want, locally and offline. Another tool worth looking at is Caret, a great imitation of Sublime Text that runs as a Chrome app and supports multiple cursors.
I get 3-4 hr battery life, but I have the stock battery. There are others available with 150% the capacity of the original.
Speaking of upgrades, the Acer C7 is the most easily and possibly the only upgradeable chromebook. It supports up to 16GB RAM and any size laptop hard drive. Mine came with a 16GB SSD, of which 2.3GB is available with a full, well used chrouton install. I am thinking of upgrading the RAM as 2GB is getting tight with instances of chrome running under both operating systems. Having a computer with a 1:1 ratio of RAM to hard storage would be kind of strange.
Overall, the keyboard and screen are really nice. The touchpad is what could be expected for $200.