At F check-in last month, I thought I was told that I had a choice of either the meal voucher or access to the Suite lounge, but was confused. I went to the lounge and didn't bother with using the voucher. Is that really the policy for F also, or is it only for C?

They are definitely giving priority to F pax even in the C lounge. There were sections of the C lounge at Satellite 5 that had signs reserving seats for F pax.