The minis for Metal Gear Solid would probably be mini-Gekkos, or perhaps more hilariously, mini-cardboard boxes that move around when nobody's looking at them.

Just my thoughts on the subject.

The first time a name is misspelled for a given universe in a mission, the writer of that mission gets to decide what form the resulting Minis take. According to the list of killed badfic on the Wiki, no one has done a Metal Gear mission yet, so I assume the Mini is still up in the air.

I have no idea about whether MG has an OFU yet. Try checking the list at the bottom of this page:
http://www.misssandman.com/LOTR/ofum.html