As far as Ive read they are still selling stock cameras and may continue production as soon as these are sold. The last production batch was made in 2008. We had a thread about this recently. Zeiss has however stopped producing the lenses. As for the portrait lenses: Everything in the 80-250mm range can be taken into consideration. 80mm is more for full length or half body shots. 100mm and 120mm I would use for half body/head and shoulder portraits. 150 and 160mm are well suited for head and shoulders or head shots, as is the 180mm. The 250mm is quite long. I do not like it very much because its quite slow also and needs a tripod. Then there is the 350mm, but its even larger and heavier of course. Apart from what Ive said, there is no problem in using a 180mm for full length shots too. Ive seen some great pictures made this way. I would however never use the 80-120mm lenses for tight head shots, since proportions will definitely look odd.
Concerning sharpness: Lenses are all sharp but some more than others. If you want the highest sharpness and contrast, go with the 100mm, 120mm and 180mm lenses. 80mm is pretty sharp too once stopped down a little. I found my 250/5,6 soft. (I have a Rollei, but lenses are the same) My 150mm is quite sharp but lacks a bit contrast (I have the version with single coating). I would rather make the choice on angle of view needed. The CF lenses offer the best value for money.