I wonder how Han plans to fight, but they're dealing with generals who tend to drag others into their own pace. Actually, I guess Shin has already spilled Qin's plan; aggressively heat hunt the generals of Han and then the Han soldiers will surrender.
Shin is already taunting the opponent generals; he's going to fight right at the front. The Han generals will be cowardly to not do the same. I'm guessing Qin is going to put its best foot forward, using their battle hardened soldiers in the front in order to pressure Han soldiers. Shin does that naturally by calling out for the glory of taking the enemies' heads so his strongest troops, who have been promoted, will seek further promotions through their own accomplishments. Then the Han generals will have to step forward themselves in order to prevent the flow of the battle from going Qin's way.
The 30000 additional troops from the various cities that provided reinforcements will definitely immediately surrender once things go bad, and when the remaining soldiers see this they will also surrender. They'll have lost too much morale. Those 30000 reinforcements will become a poison for the Han army, that ensures it doesn't viciously struggle when cornered.
This should ensure minimal losses. They'll then go in Shintei and execute the king and the top officials who argued against surrendering while the princess will be convinced to work for Qin. Han, who sees that their princess is treated well and that the Qin rules are fair to all, should then be compliant in supporting Qin. If Tou and Shin can successfully hunt down the generals of Han and avoid losing too many of their and the Han's troops, that's a lot of Han professional troops who'll be keen to keep their jobs. Han troops contributing to Qin should also help Han citizens to get better status in Qin, since regardless of their ideals Qin citizen will likely look down on citizens from conquered countries.
It seems the march to the battle slow enough for the neighbouring countries' scouts to get the information back, but they're all far too passive in helping Han. What's the point of rushing to Han after the battle is over? Qin has prepared their fresh recruits for a year, and they've just been in a staring contest with the Qin armies blocking their ability to reinforce Han but now that Han is fighting a battle for survival, they'll rush out and obliterate those armies and have the strength to also recover Han? Well, I understand why they wouldn't be keen on spilling their own blood for another country especially when it seems like Qin has poor odds of even just winning to start with (their army is outnumbered and consists of a good number of fresh recruits); it's easier to let things play out and let Qin exhaust themselves. The armies stationed to prevent reinforcements have also had to spend that year away from their homes, in enemy territory, so that has to be unnerving and exhausting. Hopefully that year has been spent harassing them but I suspect they've been complacent. Well, history tells us that they'll regret their inaction, but hindsight is 20/20.