Builders so called 'discount' - he is charging you more for the other 5 so I would think you would have to average out the cost over the 6.
If using a company beneficiary then the company will pay company tax rate on the income = 30% whether capital gains or income. But once the money is in the company it loses its character so while it can be retained in the company and paid outin lawer years it won't be capital gains when paid out, but will be dividends.
Correct, however if the 6th was held in ones own name and the builder charged $1 to build it, technically the capital gain would be offset as a PPOR?
I understand your comments re money being stuck in the company.