Yes the mix sounds right. US members know about the best mixes
Hamsters can technically have an allergic reaction to anything, just like humans. This can happen with wood substrates, regardless of whether it's softwood or the safer hardwood - which is why a lot of members now use paper based substrates.
Hamsters eat a lot of things that aren't in their wild diet, without issues. Ours have had pheasant and grouse on rare occasions! The odd bit of plain cooked chicken. I used to get them a tiny bit of leftovers if we had roast meet - that depends on the hamster - some of them would eat it straight away - nibble as much as they want and leave the rest. Others used to pouch it so I didn't give it to them as then you have to poke around in the nest to find if they've hoarded it and it could go off.
I don't think it will do any harm to give a hamster an occasional shrimp - but check the salt content on the jar as too much salt is definitely bad for them. Ie if it's freshwater or saltwater shrimp. And assume they are cooked before dried? Uncooked shrimp is definitely bad for hamsters. It does say large shrimps for turtles so I would be wary of the salt content.
If your hamster has an allergic reaction you will know, but I haven't heard of it. you might even find the hamster turns their nose up at it! Not all of them like mealworms or shrimps.
For protein supplement, these can be used as well or instead. And mealworms do tend to be popular.
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