We read the medical preparations chapter from The Capable Cruiser. Lin and Larry recommend not only the Red Cross CPR and Wilderness First-Aid classes but a more intensive multi-day emergency medicine seminar (e.g. Wilderness Medical Associates' "Offshore Emergency Medicine", Dickie L. Hill's "Medicine at Sea") for folks who are contemplating long-term cruising. The seminar will probably run about $1500 for both of us, and the Red Cross class will also be a couple hundred dollars apiece. As shipboard references, they recommend Your Offshore Doctor: A Manual of Medical Self-Sufficiency at Sea and the Merck Manual of Medical Information.
For kids' health they say the biggest issues are ear infections and infected coral cuts. For ear infections they recommend a drop of oil in the ears before swimming and alcohol swabs twice a day as preventatives. For cuts, they recommend something called Silvadine.
It seems that a number of cruisers are supporting themselves largely by writing online. I think the model is basically write a lot of good content that draws a lot of traffic and make money on the ad revenue. Maybe then you also get a weekly or monthly column in some publication, and you may also get some level of sponsorship by equipment manufacturers too. For that kind of thing, I think the key is great pictures which just so happen to feature some item or other. It probably helps to be photogenic.