In the absence of an agreement to the contrary, the seller may become liable to pay a brokerage commission even if a sale does not occur, or to pay more than one brokerage commission. If the agreement allows the seller the right to negotiate on his or her own behalf, for example, you may avoid this problem. A lawyer can explain the effect of multiple listings. He or she can negotiate the realtor's rights if the seller withdraws the property from the market, or can't deliver good marketable title.
A broker generally serves the seller, and the lender is obtained by the buyer. Both want to see the deal go through, since that is how they will get paid. Neither can provide legal counsel. If you want peace of mind when making one of the biggest purchases of your lifetime, you should consider speaking with an experienced real estate attorney.