First answer to your first question i.e. how to transfer money from India :
An NRI can transfer out of the NRO account subject to production of documentary evidence in support of acquisition of such funds along with a certificate by a chartered accountant in Form 15CA and 15CB. The transfer will be subject to payment of applicable taxes. So far the amount being transferred represents balances for which tax has already paid or exempt there shouldn’t be additional tax.
Second question transfer of funds by selling property
Profits earned by selling property in India will be liable to Capital gain i.e the difference between the sale value of the property and its cost of purchase.
Short-term capital gain i.e. property held for less than 36 months will be taxed at normal slab rates and long-term gain will be taxed at 20%. If a property is sold after being held for more than three years and the proceeds are reinvested for purchase of a new residential property, then the capital gains will be exempt to the extent of the amount reinvested. The exemption is subject to the new property being purchased within a year before or two years from the date of sale, or if new property is being constructed within three years from the date of sale.
After paying the above applicable taxes you can transfer the amount outside by obtaining form 15CA and 15CB.