You shouldn't have to build OpenWrt.  Check out the wiki: http://wiki.openwrt.org/toh/tp-link/tl-wr703n

Also, here is a terrific, image-documented guide for flashing (and deciphering the Chinese interface): http://www.madox.net/blog/projects/tp-link-tl-wr703n/

I used the images from openwrt.org, not any listed on the madox.net site.

I have several of these, all v1.6.  You might need to pop open the case and look for some internal markings/stickers to verify the version number or check the build version listed in the Chinese firmware.

I can't provide any assistance related to the Avalons, and I'm surely not anything more than a casual user of OpenWrt, but I'll try to answer any more questions that you might have.