Excellent summary Sveinn. Nice to see a recording of many of crossings across Iceland.
I would like to add to the summary, the 1 month long solo crossing of Gudmundur Eyjolfsson in 2001, from NE to the NW, passing through the Highlands.
Sveinn mentions the crossing of Vatnajökull Glacier on bicycles in 1992, an article written prior to the crossing can be found here.