ok so i havent read through the whole thread so sorry if im repeating anyone.
4 plants max in flower means your going to be either looking at harvesting 2 plants every 4 weeks or 1 plant every 2 weeks. whichever you choose all you need to remember is to take your clones every 2 or 4 weeks depending on which way you want to go. just keep taking clones once the first ones are to the size you would like put it in the tent, the rest will follow suite.
for 4 plants in flower i dont see why you would need anything bigger than a 3x3 tent and a 400/600w HPS for your flower room and you can save a bit of money on electric going with T5 for your veg cab which can be a smaller tent, i seen a 1.5x1.5x4 ft tent that would work nicely.
really all you need to do is just make sure you take them clones religiously and your perpetual will come together in time man, always take more clones then you need, you can always just destroy any you dont have room for or give em away to other patients.
as far as a mother, just take your clones off the next set of vegging clones to go into the flower cab and you wont have to keep a mother around (unless you want to)