1. Yes on RGB. Depends what IR you are using. Thermal doesn't generally work.
2. 75% should be considered the minimum overlap. We recommend using 80%. You can use as little as 20% when making a Flat Map.
3. The Mavic 3 Enterprise Thermal is supported but none non-enterprise Mavic 3 series is supported because DJI doesn't offer 3rd party app support for those. The Air 2S is supported.