The first one has been noted already. Since raising levies does not assign generals automatically raising a retinue should not either. Actually I really don't mind them assigning existing courtiers as much as I object to spamming and spawning new ones for every 500 men of the retinue.
The second thing that would be nice in the general selection screen is a hint if they are already generals. Right now there is no such hint and it is easy to pick the guy with highest martial only to find that you took him away from another army.
The solution is simple. If you marry off a general in the field in the marriage screen you see a blue sword in the bottom right of his portrait denoting he is a general. Just apply that blue sword in the general selection screen too so that we know that there is an army needing its leader replaced if we select him.
The second thing that would be nice in the general selection screen is a hint if they are already generals. Right now there is no such hint and it is easy to pick the guy with highest martial only to find that you took him away from another army.
The solution is simple. If you marry off a general in the field in the marriage screen you see a blue sword in the bottom right of his portrait denoting he is a general. Just apply that blue sword in the general selection screen too so that we know that there is an army needing its leader replaced if we select him.