1) Cost to the previous owner would be considered. Holding period of previous owner would be included in holing period. Benefit u/s 54F and 54EC is available. LTCG rate is 20%+cess @4%. If land was purchased before 01.04.2001, you may consider SDV if it is more than actual cost of acquistion of the property.
2&3) Exempt in the hands of recipient. Money gift should be thri=u banking channels.
4) Correct
5) Stamp duty value/Guidance value. Value on which stamp duty is payable.
6) ITR-2 or ITR-3