I think 'Hot!' is a special case, so it deserves its own (optional) tab on the main navigation menu.
But I've also added it as one of the sort options on the Questions page, since I agree it also makes sense there as well.
As for 'All Activity', this is kind-of different, because it doesn't just show information about questions, but also answers or comments on them.
Having said that, in the long term, I guess all of this is going to have to be customizable!