Group Purchase website CMS, how to solve

Group Buy website CMS
Just received a project, is a pseudo-group purchase site, online to buy the way to place a single, offline trading funds.
The approximate function module has the group purchase (only then the order can), the auction (4 kinds of Auction mode), the member (three level member).

1, want to consult the experience of the great God, there is no good point of the CMS recommendation? Or is it like this project or do you specialize in writing a set of convenience points from scratch? Never took such a big project, the heart is very disturbed to say, a simple use of a few CMS, but if said to write from scratch, the heart is not the end. So ask the veterans, how can I do this level better?

2, yes, there is a problem I would like to ask the big God here, this member registration needs to ensure the quality of members, the best way is through the mobile phone verification, after registration there is a verification code, only after you have the correct input sent to your phone verification code can be registered through. In short, one purpose is to make sure that every member is real, not confusing. From the customer's point of view this is the best. But this SMS gateway interface has never been contacted, find some information is also donuts, the official things Leng did not find. Do not know whether the great God has done similar, help to point a direction. or other ways, as long as possible to ensure that the membership information of the real line can be.

3, there are a lot of assorted functions, such as calculators, I bought this thing to spend how much money, and then all kinds of tax together can draw the final price.

4, also call the electronic map, etc... Electronic map words Google's better or Baidu's better? I also need to mark a lot of things on the map.

The above is my concern, I hope that experienced help to point the way. is mainly 1 and 2 of the problem, 1, this set of sites have a suitable for my needs of the CMS, no words are changed or write their own. 2, how to do this verification, so as to ensure the authenticity of members.

------Solution--------------------
With Ecshop two times development should be able to meet your requirements. Of course it can be completely re-developed. Your problems are not a big problem, you can go to the official look, it should have been done

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