As with buying any component a little research is required on your part.
To be blunt i've never heard of Power Tree, looks like crap to me after a quick google.
180 joule protection! seriously mine has 10x that.
If you had bothered to do any research you'd have quickly realized that. APC,Cyberpower,Belkin,and TrippLite are the most widely known/used.
You would also know that spending $100 would get you a reliable unit that has a replaceable battery and application software.
And yeah that's for exactly what it says it's for.
What don''t you understand?
Lots of people have phones and all-in-one fax/printers.
Unfortunately I don't think this UPS has anyway to automatically turn off your computer, it is lacking a way to connect it to your computer. Normally there is a management port that goes to your computer, but the manufacture lists no such port on there website.
Also to the best of my knowledge no UPS will turn back on your computer, at least not in the consumer category, that is more of a server thing.