Planning to buy, need a few clarifications about unit upgrades please.

[^5geebee]

Ok so ive been a HUGE fan of disciples series.The most fun part of the whole series for me was to grind for exp and then see my measly devils evolve to demons, -> moloch etc. I loved these big power spikes per level.
However I have heard that in disciples 3 there are sub levels which a unit gains in between it's upgrade so that the next unit upgrade is just a little bit more powerful than its previous form. I have 3 questions..

1. Does the unit gain sub levels in renaissance and reincarnation both? What about resurrection? whats different in resurrection compared to reincarnation?

2. Does the unit gain only 3 sub levels before evolving(heard that somewhere). So if a squire gets to level 3 and gained a level, it will become a level 5 knight... and if a knight levels up to level 7 and levels up will it become a level 13 infernal knight?