Booking new apartment during pre-Launch

APARTMENT IN EMPRASA SMART CITY http://www.moneycontrol.com/news/features/bangalore-realty-gets-startup-boostsmart-city-option_4315301.html http://economictimes.indiatimes.com/small-biz/startups/square-yards-sells-450-apartments-at-bangalore-emprasa-smart-city-in-3-days/articleshow/49980114.cms builder Artha properties and marketed by sqaure yards. I booked an apartment during pre-Launch for 25000 , post which i received confirmation on booked flat As part of the booking they are asking 100000 to block the apartment . post which legal document will be shared . The builder confesses the project approval is still pending . The marketing company says no emi till possession but from the sources i hear its only for 3 years the emi is paid by company building. What are the questions i need to ask them in mail before proceeding ? is the mail conversation considered valid by court in case of dispute? and what are the document needed to proceed further? all the conversation till now is in with square yard , i got a mail asking the balance to be paid in name of hoskote neo homes limited in cheque / online transfer post which agreement and legal process would begin. Have absolutely no info on exact location / current status / pending approval /when project will be launched/construction specification/exit clause , in fact no clear info on anything .