Capital gains on sale on underconstruction property

had couple of queries pertaining to capital gains applicable on sale of underconstruction property. 1)The first allotment money was paid in March 2010 whereas the provisional allotment letter was issued on July 2010. so if the property is sold today -long term capital gains is applicable from March 2010 or July 2010 ie the date of issue of provisional allottment letter. the property is still under construction 2) if the property is jointly owned by two- can the tax liablity be shared based on equal distribution of profit on sale on the property

Thanks