Regarding Quest +1, I'd assume this is some kind of placeholder and that Discovery have a long-term plan for the slot.
IIRC at one time the Discovery on-demand services were split into two options - Factual On-Demand and Lifestyle On-Demand (I'm possibly thinking about the old original TalkTalk/Tiscali/HomeChoice system there), rather than divided into individual channel brands. It's also worth considering that Discovery have been boosting their FTA presence in a number of European markets recently to make smarter use of their content and rights. So here's what I think may happen in the longer term:
- Quest partially retooled from its current provision into a male-skewing, primarily documentaries and fact-ent channel, screening content from Discovery, D. Science, D. History, D. Turbo, D. Shed, and maybe Animal Planet, alongside much of the current Quest output
- the Quest +1 slot used for a female-skewing factual and lifestyle channel (designed to compete with Really, ITVBe, and to a degree the likes of Pick and More4) screening content from DMAX, TLC, Home & Health, and ID as well as popular-factual Discovery programming.
Whether this would be by way of a relaunched DMAX being punted onto Freeview, or the creation of a new channel entirely, I don't know, but that kind of reshuffle would further strengthen Freeview's mix of editorial output, provided they don't just use it as a dumping ground for the same stuff already looping around on other channels...