MLS listing or through an agent

[Abhilash Joseph]

To buy a house - 

a. if a desirable/investment property is found/located, Is it necessary to have an RE agent representing a buyer?

b. Can the buyer get in touch with the listing agent @ zillow.com or har.com and negotiate directly? Is this possible?

I ask this, because the houses short listed with RE agent's help has not motivated me to action...What could I be doing wrong? I am saving up money to do a deal as soon as it comes available, but...the question above haunts