@timjim2 The Destroyer question is easy. According to rule 9.10 in version 3.0 of the Rules, “Submarines have first strike unless the Enemy has a Destroyer present”, so clearly one Destroyer is enough to prevent all first strikes. No rule suggests that you have to match each submarine with a destroyer.
To your first question, the “steps 3-7” reference seems to exclude repeating first strikes in step one, but I must confess that I have been playing with first strike on each round. Thinking about it, once the battle has started, the surprise effect would be lost after the first shot is fired…
If this is correct, the same would apply to artillery in land combat, as per Table 9-2. We have also been repeating the artillery first strike on each round of combat…
So, you ask a good question. I would like to know also if there is only one first strike round, as the rules suggest.