I'm VIP and have only ever been VIP, so I don't know which quests are free-to-play. It would be nice if there was some way of knowing whether a quest is f2p or not when you put an LFM up. There have been cases where I've not known that a quest was f2p until we tried to start and someone had to drop because they couldn't get in. So either a light on the LFM page when you pick the quest from the list, or else a symbol in the quest log (the big list, so it's easy to spot f2p quests at your level). Again, this is for people who aren't f2p themselves but want to know whether someone else will be able to play.
For that matter, if someone clicks to join a group and the declared quest is one they don't have, perhaps they should get a warning message. Or direct them to the DDO Store :-)