Keep in mind that Synth V has poor support in English. And, I haven't seen any sort of comprehensive manual/tutorial that is available. Your best bet to learn this is to watch some of the fairly decent videos on youtube. As I have learned, not everything is covered in those videos. When you watch them, be prepared to stop, rewind, and take notes. When you don't find the answer you need, you can always ask the folks here who use SV.

The user manual Noel linked is pretty good but basic. It really doesn't go into depth but it;s a good start.

Regarding the databases and the results you will get. It's not a magic wand that you can load up and get a Grammy award winning performance out of. To get the good stuff, you really have to work on the details of the voice, the note parameters, and all the little things that goes into that vocal performance. You can get it good enough to fool professionals but you have to work on it.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.