For the headset, I got a LogiLink HS0002 as first measure, which will fit the T60 directly. Although I ordered both the Y-cable proposed by AVG responding as well as the reverse version (to connect a two-plug headset to a integrated jack).
I do not yet know what will really suit me, because for earphones alone I am used to ultralight things which procect slightly into the ear without plugging it with a very light folding frame. Finding somthing like this with a mic would be lovely. Maybe I will try a PLANTRONICS HW540 EncorePro. Anything that is closed and/or puts pressure on my head and ears is a no-go.