For Linux, I've been using Ubuntu for quite a while now, but just to make things extra painful I switched over to the 64 bit Ubuntu. I do not recommend 64 bit for newbies (technically there is no 64 bit Wine). Also I have reasonably big iron with an X2 4600 cpu, and even then, GUI redraws of Karma are slow. But Wine has improved a lot over the last year or so, including much needed work on sound handling just recently, and is on-going.
It was a much bigger problem to get Fruity Loops going than it was Karma, but I used the Wine AppDB cheat sheet, so I had help.
There are other ways to approach VSTs under Linux, one being LMMS/Vestige, which is a bit unstable, but there is at least a proof of concept in that it uses Wine to handle the VSTs but LMMS is Linux native itself. Another program to watch is Energy XT2, which is Linux native, and will plug in VSTs that use Linux GUI calls (so far anyway). For Karma synth to work that way it would need to be coded/compiled so as not to use MS-ish mfc42.dll, etc for graphics calls. Hopefully Kasper was using JUCE, or wxWidgets or something cross platform like that so this will be easy to "fix"
Also I discovered that msvcirt.dll is another dll needed for Karma to run under Wine, so you'll need to copy or link that in (for now) too.
I would love to help, but unfortunatly I don't have a linux machine to test on, so I really can't answer your questions.
The "unable to load core dll" message appears because the synth cannot find the "KarmaFX_Synth/KarmaFX Synth Core.dll" file. This file is used by the VSTi and the VST (fx). Please make sure the directory is there and contains the file.
If someone reading this has got it up and running, please write and let us know how you did it.
err:module:import_dll Library MFC42.DLL (which is needed by L"C:\\Program Files\\VstPlugins\\KarmaFX\\KarmaFX_Synth\\KarmaFX Synth Core.dll") not found
but over in GUI-land the message is "Unable to load core dll".
Also I noticed that when I hid msvcp60.dll and msvcirt.dll that Karma synth did not issue any complaints and seemed to run fine, so maybe those dependencies are satisfied natively by Wine now (I was using 0.9.46).
One problem you may discover is that clicking the logo to get the info/version window will result in not being able to dismiss the window and will probably make your host inaccessible. This "bug" does not happen in Win2000 with KarmaFX 1.00RC4 so I am reasonably sure this is a Wine problem only.