Of course, if it's followed by a valid identifier character, I'll add braces: "${basename}_$num.txt"
I'm pretty inconsistent when globbing: "$HOME"/docs/* or "$HOME/docs/"* are common for me.
I don't use "${HOME}" unless I actually need the braces. The reason? I write more Zsh than anything, and the braces are even less necessary in Zsh: $#array[3] actually gets the length of the third element of the array, rather than substituting the number of arguments, then the string 'array[3]'
I always brace my variables.
While I also use ZSH, I write most of my scripts in bash because they more often than not need to run on a CI/CD server.
Depends. I use G'MIC (Interpretative language for image processing largely inspired by bash) in CLI.
ig "C:\Users\User.."
If I need something with '$' in CLI, I'd be using $_path_rc\something_something. Sometimes with "" in case of spaces.
Other than that, I would be just running my own coded command in most case.
2nd one, feels natural as a programmer.