Yes, foreign, non Swiss resident pilots that have an IPPI-Card, Stage IV or V are allowed to fly occasionally in Switzerland hang gliders and paragliders. Flying tandem and working as an instructor however is not allowed. Note that to fly cross country a Stage 5 is required.
There is a third-party insurance required, coverage one million Swiss Francs (Frs. 1'000'000).
It is recommended to have such insurance.
Yes, if they become also member of the Swiss Hang Gliding and Paragliding Association, we can offer a third-party insurance.