hi friends! i got an email from my lawyer saying that my h1b petition was selected. the lawyer sent me a receipt number of form EAC-**-***-*****. Upon checking the status in uscis the status of the application is as follows:

Case Was Received

On April 11, 2016, we received your Form I-129, Petition for a Nonimmigrant Worker, Receipt Number EAC**********, and sent you the receipt notice that describes how we will process your case. Please follow the instructions in the notice. If you do not receive your receipt notice by May 11, 2016, please call Customer Service at 1-800-375-5283. If you move, go to www.uscis.gov/addresschange to give us your new mailing address.

So my question is, did I win the h1b "lottery"? Is it still possible for me to be rejected?

Yes, at this point you got selected, approval depends on your paperwork.

How likely is that my application will be approved? Better, what are common reasons uscis rejects applications that made it past the lottery?

As long as you submitted all the documents, you will be approved. In case , if you missed some documents, they will ask for further evidence. You will have enough time to respond. If you fail to provide additional documents in that case, it will be denied. If you have actual client you working for, and you are in your field of study, there should not be a problem at all.