No worries mate.. You don't even need to use all the holes for mounting the bracket.. It's wayyyyy over built.. Four holes per each !? Two or three (for each 4 hole plate) is plenty.. It's only sheer weight we're working on..
As for alignment, the supplied template works like a charm.. Drywall is so forgiving, you can be off a tad and still make it work, without making a mess of it..

LFE ! The rest is just details..