If it's a modern fnm or something and some dudes bringing eggs, then yeah, it could take longer if they're new to the thing and screwing up their triggers and making illegal plays and etc. However, an experienced player should honestly combo out pretty easily and without much trouble.
If BUG delver becomes more of a thing like it is in legacy, I can easily see it getting some play. It's fairly easy to manipulate early game and by the time that you'll have trouble choosing what many type you want you shouldn't be having mana problems anymore.
Just from my playing around in standard before rotation (and a little bit in modern), I find that reforge the soul can really screw yourself over since it essentially fills your opponent's hand for you. In a very aggro-dominated format, this can get really tricky to play, especially against dredge decks (not super popular but dumping a vengevine and stinkweed imp into the opponents yard is never fun), and really any deck with super cheap spells. Essentially, I feel that you need to win the turn that you're playing it or you will probably get dumped on the next turn by the onslaught of burn, haste, discard, or whatever the opponent is going to throw at you. Don't get me wrong, it's great to epic experiment into one, but it can really screw you over just as much as it can win you the game.
if you dump bob and goyf you're killing so many decks beyond jund. The idea of bannign BBE is to nerf jund and jund alone. If you ban bob, doran decks will be very unhappy (I think some swords to plowshares variants and w/b tokens run him too). If you ban goyf, sure, jund gets worse but you're also making RUG delver way less fun, again, doran decks are unhappy, and so are a few others. Jund is a strong deck, sure, but there's no reason to ruin the format by banning bob and goyf. Also, goyf is being reprinted in modern masters in june... they're not going to ban him.
You are correct. When you cast a card with cascade it goes on the stack, then the triggered ability above it. The ability resolves, and you choose whether or not to play your blightning. If you do, it goes on top of the stack, and the stack continues as normal.
I've tried modern mill on cockatrice with my buddies more than I care to admit, and it's so reliant on topdecks it's just a real pain honestly. I agree with everyone saying it's a bad burn deck. In addition, many decks are totally okay with having some stuff in the graveyard, because for those decks, it's like drawing free cards.
This is a silly deck.
Seems fun to play though