MS-50 filter

[jorgen.bergfors at idg.se]

I had a look at the MS-50 VCF/VCA schematics at Music Machines.
Here are a couple of questions for those in the know:
Do the diodes in the CA3019 need to be thermally coupled? Or can the CA3019 be replaced by matched 1N4148s?
Two 100k resistors in the VCA are corcled. Does that mean that the should be matched? Or something else?
What control characteristic does this filter have? 1 V/oct or something else?
Is the VCA linear or exponential?

/Jorgen