Some flickering on the OSD is normal. The canon firmware and CHDK are not aware of each other and fight over the display. How apparent this is depends mostly on Canon settings: When if the canon UI is updating a lot, it will happen more.
If you can give us an idea how old the previous build you were using was, that might help us understand the differences. The actual version would be ideal, but just a year / month would be helpful.
2) Zebras are not displayed, although the feature is enabled.
3) Gridlines are not displayed, although the feature is enabled.
This could happen if the CHDK modules are not installed correctly on your two partition card. The boot file (DISKBOOT.BIN) needs to go on the small partition. Everything in the CHDK directory should go in the large partition. The PS.FIR file should go on both, so you can manually load with the "firm update" method to switch back. For simplicity, you can just copy the entire CHDK install onto each partition.
