I have my Profi Car 403 since more than a year and it came with a 1500 mAh battery. Are you really sure you have 600 mAh inside?
Regarding crystals the Multiplex are expensive but are very precise and should work for long. I have some Multiplex crystals here more than 20 years old and still working perfectly.
I never tried the 60 Hz option but I´m using Futaba receivers only and no problem. R103, R123 and R133 are working for sure. Also a KO 297 receiver is working.