Hi Dimitris,
Why do you think that the michahellis in #5 is a 2cy bird and 1st winter? It´s from 30 October, which means that it has completed it´s first primary moult, and shoud thus be 2cy, 2nd winter. I think it´s a 1cy, 1st winter, because the primaries looks like 1st generation, due to pointed tips, although those whitish tips to secondaries and inner primaries should have worn of by now. It seems to have moulted all it´s upperparts, many tertials and some inner greater, median and lesser coverts. It looks to worn and bleached to be a fresh newly moulted gull. The complete moult to 2nd winter is variable in time, some finish in early August, some later in Sept. Oct. If this one has finished early, it would be rather worn late in October. So age is uncertain here, from these images. Just to show variation in moult,
check these 2cy from Romania in August:
http://www.elisanet.fi/antero.lindholm/public_html/lokki/mica2kv.htm
And these 1cy Romania in October:
http://www.elisanet.fi/antero.lindholm/public_html/lokki/michahellis1cy.htm
And these from Spain in late Nov. (It´s said that eastern michahellis moult less coverts in 1cy)
http://www.xs4all.nl/~daarruud/micha/micha1a.html
http://www.xs4all.nl/~daarruud/micha/micha1b.html
I also notice the unmarked axillaries. It´s def. a michahellis, as you mentioned yourself.
The seckond gull is also a michahellis, bill shape like michahellis, probably a 2cy type. I can see your Caspian point here looking at image 1, and maybe you are thinking of the white head and underparts, and maybe structure of it, but michahellis can look like this as well this time of year - again:
http://www.xs4all.nl/~daarruud/micha/micha2.html
JanJ