Yes I checked that, the address was funded by their deposit addresses. ~600 different ones IIRC. Which is a reasonable amount of players for a new dice site.
Yes, it appears that all TX's into that address are from the DaDice Hot Wallet.
The vast majority of the remainder of the transactions out of the 1HMAg.... address are for dust amounts (under .01).
I would also question how exactly their large investors ever got their money to them in the first place. In theory their investors would deposit into their deposit address, that address would be spend-linked to the rest of their deposit addresses and then it would be moved to cold storage. However this is clearly not the case. There are no large amounts going into or out of the two known DaDice wallets (mentioned above) of any meaningful magnitude.