Glad you like it! This is very similar to a deck I ran last month, so again, proceed with circumspection. On to your questions:
1- Mystic is definitely a solid choice. Moreso now than ever in a chip-heavy (notably punish and mantra’s removal suite) meta. However, kaleos’ greatest strength lies in his ability to control trades- when and where they happen- via blink, and fist enables you to get the jump on certain minions despite your own minions having low attack while also developing a body. Notable breakpoints include: fist + jammer/ panddo = 5, fist + scroll = enables 2 drop clear without general hit on t2 jux plays, enabling you to take center, katara + fist = 6 (obelisk clears). I consider these clears + burst potential superior to mystic, as clearing a threat while keeping tempo can often save you more health in the long run anyway. Also, really note the whole “develop a body” part. Kaleos needs bodies more so than reva due to the difference in bbs. A glut of removal has rendered Killing edge too all-in during the t1/2 opening plays, and fist subs in for this buff while also developing board.
2- Like terrarius and death, I don’t include painter because it doesn’t do as much as it used to. 2x for hamon+ emp is definitely viable, but not preferable in my mind. Unlike reva, kaleos cannot poop out a threat on top of painter on 7, making the play too reactive. Kaleos thrives on pressure moreso than other generals, and once he loses it, he generally… well, loses. Also, with the fix to the flawless reflection bug, painter lost a lot of pull in the vanar matchup. Couple this with premium makantor/ slasher kibble, and the poor panda patriarch had to go.
3- Enter hamon and emp. Cycle these guys vs most decks (ergo the flex spots), but they put in work once the opponent has used up 2 of his hard removal - something which often happens when they try to recover lost tempo in the early game/ inability to reach your safely positioned minions(odds are in your favor that they won’t pull a third). Hamon in particular is very strong against lyonar, cass on non-bbs turns, and aggro songhai builds, as neither have any clean answers to it. Emp can also erase wall boards vs vanar, so that’s cool. Zendo synergy also can win you games you had no business winning. In particular, I anticipate a rise in lyonar on ladder to counter mantra lists, hence why I selected hamon as a flex choice. Warning: Cycle both hamon and emp in the early game (most games, actually), and for the love of all things wholesome, NEVER drop a hamon against vanar unless you have no other play.