Sounds right to me. With tomatoes, you may mulch the plants after the fruits set.

Tomatoes require a minimum of 1" of water per week (1.5" in a sandy, fast-draining soil). You are right, deep watering is best. Tomatoes also need consistent soil moisture, as fluctuations can cause cracking and/or blossom end rot. A good layer of mulch will help maintain more consistent soil temperature and moisture levels, as well as help keep weeds down.

Don't panic if you don't have a lot of tomatoes during this very hot weather. The plants often will not set fruit if temperatures are above 90 degrees.

Rutgers Cooperative Extension has a few fact sheets on growing tomatoes in the home garden; a link for one of them is below.

Here is a link that might be useful: Growing Tomatoes in the Home Garden

My tomatoes are mulched with a deep layer of salt hay and I have watered them regularly, but I still got some BER on a few of the first ones. It does seem to disappear as a problem as the season progresses. This is about the latest I've had tomatoes ripen, though; except for a currant-type they are only just beginning to color up.

Sometimes the first crop of tomatoes will develop BER because the plant has been growing very rapidly at the beginning of the season and just can't keep up with itself. As you've noticed, it usually outgrows the problem as it matures.