I don't believe so as this is not an over commercialised spot!

No next to each other

I didn't see any signs saying they couldn't go on the beach. Also there were dogs there when I was there.

Hi Cricceth beach itself is restricted meaning there are only certain times of year dogs are allowed, there are however beaches like Black rock sands just a couple of miles away which are dog friendly all year round

Indeed there are a lot of benches along both Criccieth beaches. The Esplanade (east of Criccieth Castle) offers one every fifty or so feet. There are some on Beach Bank, which are elevated above the road and look out across the bay. There are also covered seats on the greens both east and west of the castle. They look like garden sheds, but they provide rather good shelter on windy days. There are three benches outside the Lifeboat Station. On the west shore aka The Marine and West Parade, there is a bench at the foot of the castle, another couple at the bottom of the hill and one in the middle section of Marine Terrace. Further along there is a green with benches, picnic tables and more covered seats. Try Street View and Google "Esplanade Criccieth" then follow the road. They are quite plainly visible.

Black Rock beach is just round the promontory and is sandy and ideal for families. Vehicles can go on the beach at low tide at about £5 per day. There's also a basic camping site there with toilets. Better for family seaside days than Criccieth which is shingle and smaller. Only half a mile along the beach to the tea shops etc too!