As an ECA, you should post when someone adds you as a contact and welcome them to your store, also when you add a new product or service. If someone makes a purchase you should also post a public thank you.
If you post your news in the stream, you can set it where your A2A friends as well as those in your downline will see it. If you post it on your store page, anyone can see it. So the best bet for you is to promote your page heavily.
