Hi Andrey,
You have a decent profile . Here is my assessment of your profile:
Academic Capacity: Good GPA and GMAT.
Work Experience : Six years’ experience in healthcare market research (major international agency) is decent as most US schools require their perspective students to possess 4-5 years of work ex. You seem to have progressed well in your career. However, you have not shared any information about your accomplishments and leadership responsibilities you have held in your professional career of six years.
Extra -curricular: You have some positions in university community and have been involved in occasional volunteering. That is fine. I understand that you are now doing some volunteering activity in the US. Be regular and consistent in your involvement and you will be fine.
I don’t think working part time for one year should be an issue because you have a valid reason for this decision (study English, prepare for GMAT, take some volunteering), so if you are able to justify your decision of working part time, you should be good. You can cite one more reason for moving to the US - gaining international experience.
Goals : You have a clear idea about your short term goals. ( Short term goal -development manager/ new product development manager at an international pharm. Company). I am sure you must be having some idea about your long term goal and how you see yourself progressing from your short term to long term goal.
[b]List of Schools: Your list of schools seems fine to me. If you want, you may apply to 6 instead of 8 schools. However, many people apply to 8 schools as well for the sole purpose of increasing their chances.
I hope it helped .
You may email me if you have any more questions for me.