Looking for help to develop a relevant technology for my product development [on hold]

I am thinking of setting up a small business and for that i need to develop a web portal as well as mobile app.I am looking for a advice which technology shall i follow so that i could bring the backend up fast(i am thinking of writing the services which could cater both mobile as well as mobile apps) as well as some front end technology which can be used to get things moving fast;so that things can be up and running and ready to come in the market.

some requirement for the web portal are

1). It will be having a forum kind of thing where people can came and write. 2).There will be a selection process.Like user have 3/4 options;He select and after search user gets the map with pointing out the location(result set) and when user go to that it will give information about that(like rating,name,location etc.) and on clicking on that it will lead you to a new page will all the details about it.User can write about that product as well. 3).User could come and do some online money transaction as well related with the product. 4).Buy and Sell the product as well.

Thanks in advance