1. Usually keys resurface in an unexpected place or a particularly bright moment.
2. It sometimes happens that different keys from another R4 "coincidentally" fit on it... don't you have someone nearby with several R4s? For example, with my key I can start my brother-in-law's R4 but not the other way around.... opening doors is more common.
3. Drilling out the ignition lock is a 5 minute job. You have to drill the side where the beard of the key comes, you then drill the pins. You can then twist the lock with a screwdriver so that it can come out.
To remove the lock from the ignition, normally you need the key to set the whole to a certain position before the lock can be removed.