Pauper is a format where as long as a card was printed at the common rarity, the card is playable in it (unless it is banned or illegal in all formats, of course)
The features listed on the roadmap like difficulty modes, decoration and playable TCG is not available in early access yet, I plan to add them through future updates
He is not useless without other zombies but certainly on the weak side
Of course, the above chart doesn't include all of the decks in Modern because decks like Tron (which have lands that tap for multiple mana) or decks with a lot of nonland mana sources (more on this in a minute) complicate the calculations
No, menace only works during your attack
We already know just how amazing Glorybringer is, as it has been in copious amounts of winning decks for the past year