yes, it is, and many of the teams that were put on display in this thread DO WORK only if you don't own initiative advantage or if you don't own comparable power.

depends on the version. If you use healing tips with 1st chase and giant katsuyu yes, it's annoying because most of the times you start a combo on the enemy roshi, but there are also other versions of this team. For example if you do not link the chases you just let the ignition damage go off in round 1 and you heal as soon as the round starts, basically negating the whole effort the 30 combo chase added in round 1, in the meanwhile you target with roshi and han the BD, if, instead, you use 3rd chase, neurotoxin and lightning tiger is not at all a problem, since after round 1 you just chaos BD and you kill them with poison (bd is the only source of high combo there).

lets say in arena roshi's chase do a ton of damage while outside arena, due to how resistance scales it down, the chase is mostly there to spread again ignition, and while in arena you heal 1789/1944 with mystery and ignition lands around 1500-1900 damage on ninjas that own 9-11k hp, outside arena ignition lands the same 1500-1900 damage while enemy mysteries heal 4-5-6k and your hp are way higher... So in arena you can't let ignition go off while outside arena you just let the round end, ignition do the damage and then you heal back fully.