Brain Freeze - WNDR4700

I have been a Linux user since RH 7.x (currently using Fedora 26). Yet, when it comes to LEDE I am hopelessly lost. I have downloaded lede-17.01.3-apm821xx-nand-WNDR4700-squashfs-sysupgrade.tar I am just not sure what to do with it. Could some kind soul point me to the proper doc?

Secondly, how are people generally moving files to the HD? I am stuck with samba now (CIFS=vers 1.0). NFS beats the hell out of samba (I am guessing that sshfs probably doesn't work). In the alternative I could install either SSH for SFTP or even rsync. Any suggestions?

There are also some flashing instructions in the commit:

From what I remember, you could simply flash the WNDR4700-factory.img via the web-interface. But this was a loong time ago when I tested it.