Are the retail stores accessible without paying for park admission?

No but you can get a shoppers pass to go shop. You pay for a ticket. You have up to an hour I think to shop then return your ticket by than. They give your money back, if it's longer then the hour they will charge you the full price.

no definitely not, there are a few in the park but you have to pay admission.

No. You have to pay foe admission. They have several store throughout the park

Didn't see any stores outside the admission gate

No.

The Lego stores (like the big store and the Lego factory) are past the park entrance, so most likely you will need to pay to enter the store. You may need to pay to park your car unless you mention that you go to the hotel, which you can view for free. Otherwise, be prepared to pay. Taking that aside this park may be best option if you have kids under 12 and it's their first big park experience (or Lego fans) and will not ruin your pocket, as there are lots of promotions (search the internet) for a kid to come in free with a paying adult.

If you go to the resort yes, but if you go to the park no

The best stores are located in the park, loaded with brand new Lego’s well worth the price of admission to gain access to the park.

Yes