I always kept newts of some sort and have a marbled newt now.
Best thing for them is little worms or small wood louse, they also eat the tiny crustations that be on the rocks in ponds and streams. Pin heads should be fine but I dont feed mine just crickets as there isnt much nutrition in them. I normally dust them with calcium first.
You might find they will feed and seem to do well, then their appetite goes again. I found a crested newt half frozen on a icy path. I fed it up and it was doing well for about month then it stopped eating and started to lose body weight. It was still cold but I released it when the real cold weather passed .Some species hibernate and obviously fast. Just keep them on a bit of damp sphagnum moss and try not handle them too much.
As for the species I havent a clue what they are.