1.) technically yes, but it is very uncommon for somebody to use that word. "Heartening" means something along the lines of "encouraging" or "uplifting", but I don't think I have ever heard somebody use it in common speech. It's antonym "disheartening" is, however, commonly used.
2.) Other ways to say this which you will come across much more commonly would be:
"That's encouraging" or "That's encouraging to me" or "That encourages me"
"That lifts up my spirits" or "that lifted my spirits"
"That makes me feel better" or "That made me feel better"
There are a lot of ways to say this, but I think these variations are a good place to start.
Hope this helps :)