Hi leaders!

To give you the context: I'm starting a new choir for staff and students in the aeronautical institute where I've started working, here in Toulouse (student body 1900, probably 80% male; staff including part-time, 1800, poss 60% male - no idea how this will translate into percentages in the choir itself, or indeed how many I'll have.)

The songs will be in English; I want to teach from ear (lyric sheets but not scores)... It'll be an (almost) hour-long session at lunchtime, pretty casual (who knows, a separate, more serious group that would practise after school might emerge from it, eventually...) 

I'll be using backing tracks and, to start with at least, pre-made learning tracks, I think. We'll have an accompanist for performers and I can read music and I'll have a keyboard in the rehearsal room, but I won't be accompanying during rehearsal, unless sporadically. 

The institute is willing to buy the material (tracks, etc.) , but as I have to buy from suppliers and others have to set up accounts with these different suppliers, I have to be astute and tactical in who I use (ie. use as few as possible, otherwise they'll get fed up - it's French and bureaucratic and is already proving surprisingly complicated). (I should add that I'm principally an English teacher, so this isn't my main job!) 

I'm looking at Choir Community (lots of great a cappella, but I think this might be risky to start with?) and also I had a couple of great tips (pink zebra music, choir player, karaoke version) from the Mastermind yesterday, so I'm about to look into those too.  I guess I need learning tracks + backing tracks + lyric sheets (if arranged with the oohs and ahhs in place? Who would you recommend as a one-stop-shop? I reckon I can manage 2 stop shops, but that might be it.)

Some other questions I have: 

What great starter tracks would you recommend? Especially for a choir whose makeup you don't know (I don't think I'll have a sense of the regular makeup (SAT/ SATB / TTBB?) until the novelty has worn off and it has settled down!) Probably no harm starting with Lean on Me or Stand By Me or Caravan of Love or Down by the River to Pray / Go to Sleep You Little Baby... ? 

Should I start out with two-part harmony or am I safe enough to go for three? 

Planning: Am I right in thinking that I'm only likely to get through a warmup, maybe a round and then half a song in a lunchtime, adding on a couple of previously learned songs at the end, once we get a few under our belts? 

Any and all advice/ideas very welcome. 

Thanks so much in advance :)

Fiona