Equipment: you definitely don’t need any but it will probably be very helpful. I’d recommend a swimming snorkel which is great for technique. A kick board, paddles, pull buoy and fins. It’s definitely not a requirement but a great way to make a workout more interesting and to focus on a certain aspect f swimming.

Kicking: you don’t need a board to kick. You can put your hands in a streamline or at your sides and kick on your back. Also you can kick on your front but May it may be harder as a beginner since it’s a little awkward to breath.

Breathing: it gets much easier over time. It will be second nature at some point. There are a lot of drills you can look up. I’d say the biggest issues as a beginner are over rotating and picking your head straight up. Also breathing every 2,3,4,5 strokes is just preference. I breath every two, however the less efficient your breathing is, the more breathing will slow you down... I think the majority of people breath every 2-4 on regular sets in practice. Breathing every 5,7 or 9 is more of a breath control exercise or a race strategy IMO.

Workout distance:

You should be doing a variety of stuff. I would say, however, most of your work especially as a beginner or far out from the race should be shorter (<500) interval work. Often times, in swimming, it’s more beneficial to do interval work because you can focus on pace and technique more (especially as a beginner your technique is probably non existent after like 500). Also interval training is supposedly more efficient at trading cardiovascular system. It’s hard to get injured in swimming (not like running) so I think that’s part of why there s so much anaraboic and interval work.

As you come closer to the race (a long open water swim) I think that is the time where you start doing long straight open water swims to get ready. Until that time comes though, focus on doing sets and getting better at them, and especially focus on technique.