1) Would be nicer for newer players, but once you learn the cards, and there aren't too many, this becomes less of an issue.
2) There is an invisible mulligan that will deal you a new hand one time if you have no zero cost cards in hand. You will not know if this mulligan took place. (except if the new hand also has no zero cost cards) Think of it like the old M:tG mulligan where if you had zero lands in your first hand, you could trade it in. (not the retarded new mulligan rules they have now) I suspect that you are not using enough quanta in your deck. It will depend on the cost of the cards, obviously, but a good starting point is around 12-13 quanta cards in a 30 card deck, then adjust accordingly if you have too much/not enough. I have one league deck this season that has just 8 pendulums out of 31 cards, and I've got another league deck that has more than 50% quanta cards, so it will depend on what's in your deck, but the 13/30 is a decent starting point.
3) I've never figured out the odds of winning cards, but I suspect you had a bit of bad luck there. As for the oracle, you get 1 card per day from him, so you've been playing for 3 days so far. The main reason to spin the oracle is the chance at winning nymphs, since you can't get them from spins. Other than the occasional rare (one of the weapons, pharaoh, squid, or miracle) the oracle has nothing else of significant value.
4) Score is meaningless except for bragging rights and arena deck level. You also get a lot more score/electrum for a win than a loss, so you have to lose a significant fraction of your games to go down. With your win/loss ratio, this shouldn't be an issue at all.
5) See Drake's response on how to upgrade cards. Most upgrades result in the card either becoming slightly cheaper to play, or slightly stronger; in these cases, the card becomes 'strictly better', a term as a Magic player you'll understand. (tundra wolves vs eager cadet, for instance) For example, a horned frog (3/3 for 2
) will become a giant frog (5/3 for 2: life) when upgraded. The black hole spell will drop from 4
to 3
in cost when upgraded. In some other cases, the card will become stronger, but with an increased cost; these are usually stronger, but are not strictly better. For example, mind flayer (2/2 for 2
) will upgrade to ulitharid (3/4 for 3
) which is better, but not strictly better, and there are reasons you might use mind flayer even if you have ulitharid in your collection. (I did it in championship league one season, for example, to get them out faster) A few cards will also completely change when upgraded, and are basically a new card. Chaos seed/Chaos Power, and Toadfish/Pufferfish are two examples of this.