new powder arrived, not sealed, normal ?

I’ve never gotten a powder that wasn’t sealed. It’s simple, call the manufacturer and ask them if their canisters are supposed to be sealed.

I have had some that the paper seal came off with the lid probably some of the sealing glue had them stuck together.

The foam seal occasionally comes off with the screw cap. If it's from a retailer, I'd not worry about it.

Same here. Sometimes I open the cap and the foam disk is stuck inside the lid. Check the lid, you may have two foam disks. I've found this common on the Hodgdon 1lb bottles. The foam is coated with a sticky side that is supposed to stay on the rim of the bottle, but it often gets caught on the threads in the lid and comes off.

This happens often to me. Also if I screw the cap back on with a gorilla grip and leave it for a long time it will often reseal itself again. You could always weigh your can to see if it was full weight if you are worried.

Out of curiosity I weighed an empty Hodgdon 1 pound container and it weighed 2 1/8 ounces. I weighed several unopened containers of H4350 and each of them weighed 18 2/8 ounces. So, if my scale is correct Hodgdon is giving us an extra 1/8 ounce of powder. The scale is an Accu-Weight Yamato made in Japan.