I know I used to use my laptop as my main computer and used an external monitor, mouse, and keyboard. It was a pretty nice setup, it's just like a normal computer. Though obviously not very useful if you don't use it the same place much.
As far as getting too hot, that would have to a personal choice. It's easy enough to use a cheap USB keyboard and try it out. I did find it a little weird using an seperate keyboard without an external monitor.