That's one hell of a father's day gift!
You'll be fine with a single canister, just keep an eye on CO2 consumption. A 10lb bottle would be a good investment but the pressure will be more than enough to feed 6 regulators although for simplicities sake I'd run a single regulator for similar beer type (ie, 1 reg for lagers, etc...). You'll want to replace those 3/8" ID jumper lines for the beer for such a short run, or most likely you just won't hook them up to the coupler.