Hi,
I've found this powersupply:
http://www.ebay.com/itm/5V-15A-75W-Power-Supply-AC-to-DC-Adapter-for-WS2812B-WS2801-APA102-RGB-LED-Strip-/331525055044?hash=item4d306ee244:g:BTEAAOSwpDdVJNWA
to power my led strips which will use 13A max.
But this power supply is 5v, is it possible to power my arduino with it too? (what hardware should i use)
The Arduino runs off 5V so you should be fine if you connect to the 5V pin (bypassing the on-board regulator).
With that much current, you'll probably get a voltage drop (and noise) across the wires & connections so you may need separate power & ground wires to the Arduino, especially if there are any long wire-runs involved.
You may need to add some large and small "decoupling" capacitors to provide clean power to the Arduino.