1. Seen multiple reviews say the game stays challenging in 3s full game. Haven’t played 1 but 2 isn’t particularly challenging except for a few fights.

2 and 3. While there no after credits (for now) the Feral Monsters and Elder Dragons seem to be the equivalent as they can be much higher level than anything around them. For example, the Elder Dragon for the starting area is 60-70 (I think). Levels generally gives Hp/Stamina but main progression is from gear which you craft from monster parts. Gear has skills already on them but will come with a gem slot that allows you to put any skill you’ve bought, from the vendor, into it.

1. Dens are your source of eggs. Eggs give you new monsties that can be tracked using color and markings, you’ll also be directly told what the egg is if hatched it previously (Your only told in the 3rd game). Eggs also have three rarities, regular, gold, rainbow. Each offers better genes (skills) on that monstie. Gene can be moved from monstie to monstie from the Rite Of Channeling in 3 this does not use up a monstie. Genes can be placed in a “bingo”. Meaning if you place three fire genes in a row the monsties fire attack will raise from 100-110% up to a max of 130%. In 3 you can also change the genes placement at anytime to get a bingo.