a) Start with two females (one that you choose, and one that he chooses) and set them up in a small rack (maybe 4 tubs deep). That gives you a little room to grow without it being scary, and only one set of husbandry variables to monitor during the couple of years your girls are growing up. It also gives him time to get used to caring for two snakes without the pressure of "When can we start putting them together??" Then, you can select a male together to grow when the girls are up to size. My SO thought I'd gone off the deepend when I started adding the second DOZEN BPs to my collection, but now he offers to feed (especially the babies) and change waters any time I'm going to have a late night or travel for work.
b) Quite a few breeders (myself included) will only ship "Signature Required". This reduces the odds that the package will just be left outside your door without so much as a bell ring. This also means that you need to be available to receive when the box arrives. Fedex Tracking is your friend!
Add: People only ship Mon-Wed so there is less risk of a snake ending up in transit and exposed to temperature extremes over a weekend if there is a shipping problem (delayed plane, truck breakdown, etc.).