Let me see if I can tackle your questions in order here,
As far as U.F.O. goes, this can be an intimidating trick for beginners and one that is very difficult to keep consistant even for experts. There is a much better trick for adjusting string tension that you will learn as you progess, so I wouldn’t fret over learning this trick before moving on.
The Hitman that you have has what is called an adjustable gap, which allows you to tweak your yo yos responsiveness as your skill improves. It is capable of all the tricks you will see in the learn section here, but it takes a lot of practice to get there.
At this point you want to have it as responsive as possible, so cup the yo yo in your hand holding one side steady while turing the other clockwise until you get considerable resistance. Be careful not to overtighten it!
The problem is that the bearing that comes in the yo yo is shipped dry, with no lubircation what-so-ever. Before the bearing breaks in it is semi-responsive, but not responsive enough to make a trick like U.F.O. easy.
Andre (the guy in the ‘learn’ vids) is using a YYJ Dark Magic, not to different from your Hitman, with the same adjustable gap. The reason that his is so responsive in some of the vids is because he added thin lube to the inside of his bearing, and has the gap tightened all the way.
If you want your Hitman to be that responsive, you would need to open your bearing, clean it, and add some YYJ lube.
Instead of doing that before your bearing breaks in though, I would just move on to the next trick, and let your yo yo ‘spin-out’ when the string tension gets too high. Later you will learn a trick called ‘sidewinder’ that, in my opinion, is easier to do and doesnt require as responsive a yo yo (it still has to be responsive, but just not as much).
There’s a lot of information here, but I hope it helps. Let me know if I can do any more to help.