Efficient answers for an efficient question :)
1) Fridge thing, yes. Store refrigerated, take it out 10-15 minutes before serving so it softens to the right chew. Going soft on a warm counter means the room's hot or the batch is on the soft side - if you're selling and need counter-stability, firm the recipe slightly rather than fighting physics.
2) Square silicone is perfect. Unlike moulded bonbons (which need polished polycarbonate for shine and snap), fudge and pressed bars don't need a glossy shell - silicone demoulds them effortlessly.
3) No trap. Fudge is built on sweetened CONDENSED MILK, which brings all the sweetness the product needs - the unsweetened natural cocoa balances it instead of fighting it. Sweetened cocoa on top of condensed milk would tip the whole thing into toothache territory. The recipe knows what it's doing 🙂
