Idea 1: a system of notatization with backup or not for docsdocs ... With C2C service and B2C/B one even a government to Citizen service...
What do you mean by notatization? I have never heard something like this before
If you meant notarization of a document by the usage of a digital signature, it's literally a good idea to think. But your question is not pretty clear to be answered. Consider that we need to digitally verify the signature of a person, we can do that by the usage of possible pubkey of the person. This particular kind of actions can be performed with coding of a proper smart contract. Smart Contracts can be very useful in carrying out such types of validation practices. Smart Contracts can be better coded in the Ethereum Platform with the establishment of your own token. Let us assume that we have coded the Smart Contract in the Ethereum Platform, the contract serves as the central middle-man between the C2C or B2C as you have said for validating the signatures of the other person.
Idea 2: a "meal voucher" project ... I let you develop because the stakes and constraints seem obvious to me ...
Your ideas seems to be really interesting, in the sense if they are carved out properly. Let us consider that you start up your own company and you offer some meal vouchers for your employees. In this case, these vouchers can be ERC-20 tokens. Consider tying up with some restaurants and buy back the tokens which were given by your employees to the restaurants for meal. In simple terms the flow can be like, the smart contract by default gives away some meal tokens to your employees in their wallets. They spend up their tokens by buying some food in particular restaurants. They send the tokens to the restaurant which further the restaurant can redeem from your site to their fiat money. You don't need a pay-roll or any team to order these vouchers, everything can be handled up by the contracts.
P.S I am not sure of how these ideas can be flourished with the help of ada or stellar as I have never used them. Also I think this don't seem to be a Tech Discussion in Btc section...