Yes the arrows can be made bigger ofcourse 🙂 You’ll only need to make some small css changes to make it happen. The best way to go with this, is to use Firefox in combination with the Firebug plugin, or use Chrome with the Inspect Element option (right click on a webpage). That way you can see what css you need to edit.
You can find the css in the style.css file in the theme folder. You’ll need to edit the following css:
Line 1023 to 1075 for the precious button, and line 1081 to 1133 for the next button. For example, try changing the height and width of the ‘#card-next .arrow_bit_bottom’ and see what it does 🙂
Hope this helps!