H1B Visa through Sponsoring consultant or Reputed IT company ?


    I have an approved H1B petition from 2017 quota, yet to go for stamping.  This petition was through a sponsoring consultant.

Currently I am working in a reputed software services company in India which has offices in USA. My current company also filed a H1B petition in 2018 quota and it was picked in lottery.

     Now I have two choices, to go via sponsoring consultant or go via my current employer. As my current employer in India is a large and reputed IT company, I assume that rejection chances will be less and whole process will be hassle free. Also job while in USA will be assured. I know some of my friends in USA on H1B are getting work only for 3 to 4 months in a year. 

My questions:

With the given context and my friends experiences I am preferring to go via my current employer, is this right decision ? please give your recommendation.If I go ahead and complete stamping with my 2017 petition can I go to USA and start working with my current employer with out visa transfer ? how long this process might take ?In case I complete stamping for 2017 petition, will there be any issue if I go for stamping of 2018 petition ? is it legal to have two stampings ?In case I go for stamping of 2018 petition (after approval) first instead of 2017 petition and face rejection, Can I go for stamping of 2017 petition with out hassle ?In case I face rejection during my 2017 petition stamping, can i go for 2018 petition with out hassle?Thanks & Regards