NyneAyron: Can I trade in XP's for credits? These I get when I play.
No - XP's are to increase levels, thus get better equipment.
Credits are to purchase equipment.
Earn credits via the GET CREDITS section, or buy them if you can afford to - less aggravation and painless.
Many players have top equipment and never actually paid a dime, apart from their time.
This game you have the choice - or do no offers, pay no money and still play for free.