Out of the 5 cons you mentioned, 4 is expected for any job that is fast tracked or have good prospect. All MA and MT burn their weekend and personal time regularly. Stress and steep learning curve is expected. If the job is easy anyone can do it. However the main difference is that they are generally well compensated for their time. Unless the contract you sign has specific milestone for salary increase, I'm guessing it's all smoke and mirrors.

Top talents are attracted by top dollars. If he is indeed grooming a GM replacement, why is he starting at a 1k pay? That's borderline intern pay. There's no guarantee that whatever he say will materialize, and he definitely would not put it in a contract as such stuff are dependent on performance. Most job description often sounds nice but you'll be in for a surprise when you actually work there and realize it doesn't match at all. Sounds to me that the boss wants to hire a PA for cheap rather than grooming a future GM.