BREL:
what does step 2 and 3 ( outlined by you) will do
opkg list | grep unzip
That looks in the updated package list for the unzip program description
unzip - 5.52-1 - InfoZIP's unzip program. With the exception of multi-volume archives (ie, .ZIP files that are split across several disks using PKZIP's /& option), this can handle any file produced either by PKZIP, or the corresponding InfoZIP zip program.
That is the resulting output of step 3) on his Yun. If you do not get that output (or one very close to that), then installing unzip in step 4 will obviously fail....
hth,
Ralf