Significant location change for geofencing

Question

I need to deliver specific messages to the user based on its proximity to a specific location and on some other rules (like if there are any specific messages for that area). For example User gets in car and gets to work. The moment he arrives at work he then gets a message of some sort IF there's a message to be delivered. Here's what I was thinking (no code yet just trying to design the flow while I work at other parts of my app)

1. Listen to significant location change and each time that happens send the user's geolocation to the server to see if there's any message to be delivered near that location. No go. That would drain the battery too much due to overusing the radio.

2. Save the message regions daily, and at each significant location change do a test on the local stored data. If anything matches THEN contact server. Sounds better in theory.

Questions:

1. Can number 2 work?
2. What is the fidelity of the significant location change? I would like NOT to lose a message in a specific area by not getting notified of a location change.
3. Is significant location change REALLY based on cell tower change? (i read on a number of occasion that'it is not)
4. Would region monitoring be more suited to this task? Anybody using it? What is the battery drain on it and does it have better or on par fidelity to significant location change?
5. if app is terminated will significant location change really wake up my app? kinda depending on it.
6. any suggestion on how to approach this in a way I haven't talked about here?

A million thanks to anybody who takes the time to clear some of this stuff up.

EDIT : extra question 7. Region monitoring, having a large number of regions added has any impact on the system? Say having 2 regions vs 100 regions?