Only phones with Android 5.0 Lollipop officially support outputting audio through USB, and I have my doubts that that your stereo could receive that.

Otherwise, connecting an android phone via USB will only allow you to play music stored on the phone, and only if the head unit accepts the MTP (Media Transfer Protocol,) which is what all Android phones use since version 4.x (Ice Cream Sandwich.)

Older android phones show up as Mass Storage Devices, which your head unit almost certainly supports, but this is no more useful that just plugging in a super small flash drive into that USB slot, like this one or this.

I'm one of those users who believes you can never have enough RAM :)

Perhaps a sale will come around for the 8GB/256GB one, with Amazon having a sale on the tiny flash drives, storage space can be easily upgraded: http://www.amazon.com/gp/product/B00LLEODCK/ref=gb1h_img_m-4_1087_0fee7800?pf_rd_m=A3P5ROKL5A1OLE&pf_rd_t=101&pf_rd_s=merchandised-search-top-4&pf_rd_r=0S423WRATQ5P13JCH53A&pf_rd_i=590987031&pf_rd_p=672501087