Astynax

Yeah neither. I think they're implied to be the go to objective warband but this makes them quite predictable and unable to do much else. With M2 without being inspired it'll be hard pressed to even get to objectives in the enemy territory. Looks like shardcaller is a must have upgrade for these guys too. Just sit on objectives and swap for the one you need. yaaawn lol

Will their grunt rats keep their upgrades or stay inspired when they come back or are they going to be considered to be brand new rats coming in with the same profile?

Cruel Taunt looking more like an auto include in many decks now. Useful for other warbands but massively powerful against these guys who get +1 move, +1 damage and +1 wound when inspired. Also removes crit cleave off their leader but would probably be used on someone sitting on an objective on turn 1 trying to get inspired if the leader wasnt one of them. Not sure I'd like playing them since they'll have the most predictable turn 1s of any warband so far wanting to sit on their objective to get inspired then most of the time be eating the charges.