Can this notarization be used to issue art assets/digital collectibles that can be traded on the DEX? (2)
Maybe, not sure exactly. Is a private key a digital collectible?
question 51% can be solved easily if you use not 1 algorithm and several tied to the mining devices so the attack will be not at all scary if the coin analog will be on another algorithm (completely copying the file of the main media), attacking 51% + attack =0 if there is a file restoration which would work as a backup\restoration . make more gcd on more algorithms. I'm from Russia and use Google translator so sorry for the mistakes)
I don't agree with and/or fully understand with question
How much hash required to 51 percent attack hush?
When dpow is enabled, after one notarization (one minute) to KMD it will be as difficult as attacking KMD (much larger), and after one notarization to Bitcion (10 minutes), as hard as Bitcoin itself.
Do I have to do anything with HUSH?
All Hush users that use full nodes (MyHush/hush repo), all mining pool operators, ElectrumX backend operators, all exchanges must update. BarterDEX/HyperDEX users, web wallet users or any kind of Electrum-based light wallets do not need to do anything (but the people who run the backend servers do, or their end-users will be on a fork!)
What is the advantage of BTCH vs HUSH now that Hush is KMD notarized?
BTCH inherits many features directly from KMD, this brings Hush in line with one feature. BTCH will soon fork to get cryptoconditions, which would be quite a lot of work to add to Hush, but it's possible someday.
whether the attack of 51% for KMD is possible?
It's possible to launch a 51% attack on KMD, it's just that it will cost roughly the same as attacking Bitcoin, so why not attack Bitcoin?
And 51% attacking Bitcoin is so expensive, that in practice the most valuable altcoins with relatively smaller hashrates are the "sweet spot" for mining attacks. This often means forks of large coins which have high speculative prices and very small mining communities.
Why is this the best solution to prevent attack on Hush?
KMD's notarization service is the best currently known open source way to prevent double spends on exchanges and makes life hard for 51% attackers. It does not prevent a large miner from launching a 51% attack, but it prevents the attacker from accomplishing their final goals of stealing funds and also makes life harder for evil/selfish miners.
What is Hush KMD Notarization?
It basically backups up block hashes from Hush to KMD to Bitcoin, so an evil miner cannot try to lie and steal funds from exchanges or other user. It makes it basically just as hard to lie about a Hush transaction as it is to lie about a Bitcoin transaction, with a short lag of a few minutes that it takes the data to go from Hush to Bitcoin, through Komodo.
How will the development of KMD provide value to HUSH?
Hush will now beneift from the amazing global notary node system that protects Komodo and dozens of other coins. This will prevent double spends on exchanges and also make selfish mining riskier and hence more expensive to launch on Hush, forcing these evil miners to other chains that don't have these protections.