How long will score be lowered? and will paying off student loans early do anything to credit score?

I have really good credit, welll as of a couple months ago. I just opened a new credit card, first one opened in 5 years, I really wanted a card that gives cash back as I pay in full every month so for me it is essentially free money. Now I know opening something new lowers credit, by how much? Id like to apply for a mortgage in about a year. Also, Id like to aggressively pay off my student loans and have them paid in 6 months. I Only just started paying them back a yr ago. Will this have any effect on my credit score?