I'm not really sure the manga mentioned about it explicitly, but after I quick skim the early chapters I found in chapter 4 that Greg said Cry is the youngest certified level 8, I assume it can be implied that there's not so young level 8 out there, but I admit it's not really explicit mention...
No, he isn't ordinary, he is below ordinary.
Other than his ability to use all kind of relic, having friends that can become strong with his weird training method and his luck, he is just a weak guy.
Killing a dragon personally and having a dragon slayer title isn't a same thing
If a party killed a dragon, and you're a part of that party, you'll be titled dragon slayer too even if you didn't contribute anything to slaying that dragon, especially if the party members holds you in high regard, no?
So far, only 2 irregular encounters showed up on the story, while certainly Pied Piper is a dangerous one, being an assassin type who targeted the human master, with added rat mobs summoning, he can still be easily countered. The other one, though, is practically death sentence even if you beat...
Irregular encounter is rare, but not really a big deal, especially in a low rank dungeon like this and it's only Pied Piper.
Most, if not all, irregular encounters are already recorded and have their own 'how to beat'.
As for the 20 years ago incident, it's not irregular encounter, but Dungeon...
Adventurers can have billion of cards in stock, but they only have limited active cards at the same time, based on the labyrinth's rank (F-rank only allows 2 monsters, while E-rank allows up to 4, etc). This rule only applies in labyrinth, so if adventurers can summon monsters in the outside...
Free to choose as long as the next rank card is provided as a sacrifice/base and it's from the same race (undead for undead, demon for demon) up to C rank.
There's actually a wiki of sort about evolution path of known monster, and MC did use it for his evo plan
Yes there's more evolution path for most monsters, but since MC already have magic attacker in Renka, a trickster/trickster would be a better addition for his team, unless MC wants to go all in on damage.
Since cards can evolve, and Imp is E rank card, plus this one is a rare girl card, it kinda locks her evolution path, no?
On another note, monster card as a drop is super rare, and the higher the rank, the more rare for it to drop.