I have noticed many featured studios and the SDSs do not count that as helping. It does not bother me that much, and I count that as helping.

How does it benefit anyone at all? They already know a curator will add it soon. It's not feedback, it's not useful information, it's just something that people who want to be invited say.

I agree that it's not really too helpful. Since curators have to check anyway whether or not a project can be added to the studio, saying this sort of thing doesn't really say them any time in the long run. It also makes things awkward if someone says “This will be added soon” but a curator never gets around to adding it (due to curator inactivity, lots of requests, etc.).

What I do think is helpful is if you happen to check the project and find some reason why it cannot be featured — for example, the project was made by the user proposing it. Then it should be perfectly acceptable/helpful to tell them “Sorry, you cannot propose your own project to be featured.” Then a curator could look at that reply comment and not waste their time checking to see if the project could be added.

#1
Well, They look at the oldest comments first, and it goes up to the newest comments.
Also, they have to check the games / projects / animations or whatever to make sure it fits the studio and that it's not inappropriate.

I would say that it is helpful in a way. Many people use that as a way to get invited to the studio. However, simply posting a comment like this is not really considered feedback. A more constructive comment would be like this for example, “I loved how you added the music to some of the intense parts of the project. Consider adding some effects! It should be added soon.”