Q1: Where is the firmware of RAK2245+RPi?
Fomi: By now, there are two projects for RAK2245+RPi, one is based on LoRa Gateway OS, the other is based on Raspbian OS (Stetch), both of them are fully open source.
If you want to use the firmware directly, please download the firmware here and have a look at the readme file:
If you want to get the source code and compile by yourself, you can find the source code on Github:
Q2: How about the GPS function of RAK2245+RPi?
Fomi: RAK2245 integrates an Ublox MAX-7Q GPS module, and RPi connect to it through UART . You can get the correct GPS data by using the above firmwares.