We have made some effort to implement some token canister templates.
About 3, currently we have implemented built-in tx storage and separate canister tx storage, ultimately I think we need an auto-scale storage solution for tx history storage.
About 4, fee logic is indeed needed, pay a fixed amount of token for each update call is reasonable.
About 5, I think you mean account id and principal id, here is a picture explains the different, principal id is the unique and native identity on the ic, we choose to use principal in the implementation.
About 6, I think aaaaa-aa can be used as the blackhole address, its the ic-management canister id, not an actual canister, just an abstraction of some system level APIs.