I'm also worried HOA special assessments although the unit is brand new. please help me If I should proceed with this deal. thanks 

I'm not knowledgable on the Jersey area but most townhouses are managed by a HOA with some hefty fees that eat into cash flow.

I am selling a condo in Florida, of course part of an HOA, actually multiple HOA's seem to be in the overall community.

.- Property Proce : 340k - Average Rent :2400 - Monthy EMI - 1900 (including taxes and HOA)Property Management Company Fee : 1k for new lease and 5% as monthly fees.Please advise.

We complained to the building HOA board and the other unit's owner (who didn't care), had the tenant keep notes on the behavior, called the police, etc.

No fee townhouse is a good idea(make sure you can turn it into a rental after a year with HOA) but if you get a SF around 240k it should cashflow about 200-300 assuming you can take advantage of a below 3% interest rate. 

This property also has an HOA fee of $380 for both sides.

You have an HOA which is an uncontrolled cost, high property tax, and give 8-10 percent of gross rent to your pm.

If you are financing, the mortgage company will want 3 months minimum cash reserve for your personal home (taxes, insurance, HOA, and mortgage if you have one) and the same for the place you just bought and place you want to buy.

Also, there is no HOA fees.I am using management company to find the renter and manage the property.