If you're asking if magic spells have empirically consistent effects, well...no. If they did then we'd be using magic instead of technology.
It's not the spell, it's the spellcaster. The spell helps the spellcaster make affirmations, or get more in harmony with the universe. A curse is a good way to articulate and dissociate from a very unpleasant experience, and the emotional impact from a bad experience, so a banishing spell or a curse-breaking spell does the opposite too.
Depends on a few things but yes, luck and curses are real. If you charge enough energy, focus, visualize, the spell needs to be a working spell and, of course, you need to believe in magick.
The specific spell I don't know if it will or won't work, but give it a shot. Curses are commonly frowned upon because karma tends to keep things level, and the negative effects felt by the caster is rarely worth it. But its up to the casters morality whether or not what spells they cast. Research magick so you can separate working spells from fake spells, and determine what spells you feel you should and shouldn't cast.