The EA would not normally contact you after every viewing. There's no point unless the people actually make an offer. The people who made the offer may have changed their minds and found something else since. The only time you will get to see who is buying your house is when their name and address is supplied to your solicitor having agreed the sale price and booking deposit is paid. And the only way you will know if the buyer is serious is when they sign the contract and hand over the 10% deposit.
We are currently trying to sell our house and have had 2 viewings with 2 different EA's, and each time i had to contact them for an update, i think it is important for the EA to contact the seller to let them know if there is anything that we could change that would increase the prospects of sale in the future, after our first viewing, i contacted the EA and she told me that there was an issue regarding neighbours, i told her that they were leaving 2 weeks later, of course perhaps if she had asked me the question after the viewing, the house could have been sold? however this is off topic.
with reference to the actual question, in the past we had placed an offer with the EA and then decided not to go ahead with it in the end, and they did try non stop to contact us until we were sure that we did not want to go through with it and let her know, then again, it was only 2 days! as a potential purchaser i would totally
not agree with the EA handing out my details, and to be honest its pointless, why should the EA lose out on his 1.5-2% by handing you the details? if your going to hire an EA, don't do there job, and pay them for it too! chances are if the potential purchasers haven't bothered to contact him and tell them they aren't interested anymore, they wouldn't be anyway impressed with a call from the vendor, it would be like the EA is sending the heavies round!