-The berryGPS-IMU does have an internal antenna
-To improve the signal, we do sell a ceramic antenna which would fit inside the case and work perfectly. You need to make sure it is facing up. And there is no need to mount it away from the Raspberry Pi. In fact, if it is sitting right above the Pi, the Pi can help reduce multipath errors.
-The small uFL connected isn’t meant to be frequently removed. You should be fine if you are using a SMA connector.
-To improve the reception of any GPS antenna, you can try and avoid multipath signals. It isn’t mandatory, but if you have issues, look into this.
-regarding RTC, as long as you have power to the Pi (even if the Pi is shutdown) it will still have power on the Pi 3.3v pin and therefore still power the BerryGPS-IMU.
-Acquisition, the longer it is off, the longer it will take to get a FIX. If off for one week without power, and you turn it back on while in the same position… I would expect it to take 1-5 mins. If you are moving while it is happening, it may take longer. We do sell the BerryGPS-GSM, which can get a fix in seconds.. no matter how long it has been off. But it does not include an IMU.
-Heading in Navit. Im not sure how this can be done… sorry.
-device orientation. For GPS, If you using the internal antenna.. then it is best that it is at least facing up, doesn’t matter at what angle as long as it can see some sky. If you are using an external antenna.. then the external antenna would work better when it is facing up and seeing some sky. It will work upside down.. but not as well. For IMU, it is easier to work with when it is right side up and the compass works best when the pitch or roll of the device is -/+ 40 degrees.
I hope this helps
Peter --OzzMaker.com --