actually, the Rolleinar I is very good for portraits, Rollei recommends that portraits not be taken from less than 1m away anyway to avoid distortion (unless of course that's what you're after). In any case, here are the focusing distances for the 75mm or 80mm lenses of the various Rolleinars from Heering's book:
I: 45 cm - 1 m
II: 31 cm - 50 cm
III: 24 cm - 32 cm
In terms of scales, the Rolleinar I is for about 1:6 to 1:10, the II for 1:4 to 1:6 and the III for 1:2.9 to 1:4 (again according to Heering).
The lenses can also be combined to allow extreme close-ups, but I don't think the parallax correction would work properly at such short distances and of course the optical quality is reduced.