congrats on the job!
The best advice that I can offer is to be as prepared and organized as possible. The more prep-work that you can do on the scripts before you arrive or before you get insanely busy, the happier that you will be.
2 week rehearsal periods is pretty typical in summer stock, although it is somewhat unusual for one person to stage manage back to back shows.
There a couple ways to use the ASMs, you can assign then to alternating shows, so that way they only have to concentrate on one show at a time, or you can use them both all the time. If there is a chance of the director using them as cast members, I would keep both of them on all shows so that you have a better chance of them being available to you.
Use the ASMs to track the props, costumes, be on book, etc. That will allow you to concentrate on the blocking and large scenic pieces.
I hope that helps. Good luck!