It does not matter (for what I know so far). But it is very important that the email confirmation (through clicking the link) is from the same IP as the account is currently operating on. Of course everything you do on a real device is always better than on a simulated one.
When you restart JARVEE, the account comes out of night mode, or any number of other things including what @kripke showed you, the account will sync.
No, I’ve seen absolutely zero correlation between blocks etc if that annoying little red button is there. Many times it’s only for that “device”. I might do it for Slavs accounts, but never seen the need. I had it on my app for months and the reason it went away was because my wife was tired of it.
Going into the profile tab is just what you expect, it sends an API request to open the profile. You want to avoid any actions that IG night consider high risk, like anything involving the profile. Other experienced users can chime in. But I leave it alone and it works fine