What are the system requirements for Plot2
Plot2 will run on Mac OS X 10.9 but I recommend at least 10.10

Is it possible to have transparent backgroud?
Yes, go to the General Inspector and uncheck Draw Backgroud and Draw Margins.

Is it possible to have subscript, superscript, greek letters, etc. in the axis labels?
Yes & No. This is not possible with the Axis Text field from the Axis Inspector. Instead you can use a text object with enabled auto positioning
(Example: https://apps.micw.org/apps/plot2/downloads/supersubscript.zip)

Is it possible to import my very special data format?
If the builtin import function is not able to read your data you can build tour own Perl based import module. Click here for details.

Will there be Plot versions for Windows or Linux?

I have a problem changing comment entries in the inspector
Single click on a line in the inspector to make it selected, a second single click on the comment will make it editable

Where is the curve fitting?
<strike>Iím sorry, but the curve fitting module has gone. This part of the Plot sources is not under my control, and Iím no longer able to support this within acceptable amount of time.</strike>

Curve fitting is back since version 2.6.0