Who Do I Tell How Much Cash I Have
I am a newbie in NYC, and I plan to buy, rehab, live for 2 years and sell a piece of property. I havn't found that property yet, I am starting to look for one.
My family is trusting me to deal with their cash to invest. It is a lot of cash 
Do I tell my real estate agent how much cash I have so he can guage the market for me and tell me some lending options to increase my leverage?
Do you suggest I hire and pay a real estate financial advisor to get me started (if ther is such a person)?
gemre 
I'd not jump into anything right away. Spend a little time and get to know your options first. Then, if you think you want to hire a professional to advise you, you'll have a better guage of their qualifications.
You might look into becoming a private (hard money lender) They typically invest in fairly short term deals with fast turn-over, (Cash is King), You could get good rates of return, and your investments are secured by real estate with good amounts of equity.
There are several options to you. You will need to decide what risk you and your relatives are willing to accept, and move forward within those guidelines.