Since @n1xx requested for my opinion on the matter:
We're not trying to be professionals here and this was made with the intent to enjoy the project as a community; well, that's one point down.
Although I was with the majority assuming that we are to vote for a single song and sing whichever gets the highest count, and not expecting a medley/mash-up chorus; my latter assumption, to me, shows equal promise as that of the original intent.
I've listened to a couple of mash-ups by amateur DJs/youtubers that made use of various genres so I'm giving the benefit of the doubt to the decision of the organizers here thinking if these amateurs of the field can do great mash-ups, why not us given they were once... well, us (not as CL but as an ordinary person before they underwent the field).
Though as we stand, a part of me is inclined to voice out that beyond 6 songs in a medley would indeed be a challenge, let alone difficult for not just the mixer but also the participants/singers. That being said, as others have already pointed out, they don't need to participate in ALL of the songs.
If we ever push through with a medley in the end and there are songs that are beyond the majority's vocal/capability reach, there's no harm in doing portions of the medley as a duet/triad/quartet for more variety; but of course it'll need the full support still of the majority and the selected volunteers.
How this ends up is strictly on the hands of the organizers and whichever decision they come up with, I'll gladly support it - be it for fun & convenience or a challenge-accepted mix-up; the main point is to enjoy the project.
As for the current ideas chosen,
none of them are in the position to be rejected; and though I stand in equal footing of interest on each idea, I think @Gargron's idea is already being implimented yet we're still not complete as regards to a final plan - the fact that they're asking enough input from the participants is enough to note that @n1xx and @Fieyr are planning this with us, not just them, for them to be able to come up with a final project plan; heck, we haven't even started. XD
Idea 5 shows some promise; we've already made before (in my church & family) a 6-song medley comprising of 6 songs from our Kingdom Melodies of varying tempos (not sure if that was the perfect example) - my dad who was leading the project admits it was hard and the only way to make it go well is to get portions of the right parts and blend it with the others despite the range in tempo, introduction, approach and individual melodies.
Heck, it's possible on my book so the idea has my full support if that ever came out as our final decision.
For a poll, I think as stated above we're already hosting it, as stated above, so there's no need for another re-run. You'd just have to compile everyone's feedback to see which idea is supported and which are negated since they're already in the midst of it.