You can contribute to the project by using an app like NeoStumbler (GitHub) or Tower Collector (GitHub) to submit location reports. NeoStumbler does Wi-Fi, Bluetooth and GSM, while Tower Collector can only do GSM cell towers. Both are FOSS and available on F-Droid.
Unfortunately not, since iOS does not allow third-party apps to access the APIs required for Wi-Fi scanning. I think Bluetooth could be done, but bluetooth beacons by themselves aren't as useful.