My Apollo 630 is perfectly stable for hours with the same kind of fan arrengement as seen in amiga600.de. I have too another fan on the 68030 itself.
However it is a bit noisy.
This accelerator is a pure marvel to me, i am very happy with it :-)
As for booting on CF, of course it is possible over IDE, it should be possible too over PCMCIA but the driver that everyone us with the CF-PCMCIA Adaptater is not made for that.