For shampoo type items, I feel pretty comfortable using anything marketed at human use (I suspect human products probably undergo more testing and are more regulated.) I've actually abandoned Mane N Tail because the conditioner is so "gloppy." One reason I've switched is that when the manufacturer stamps "horse" on the label they usually up the price significantly. I've been playing around with Garnier Fructis products. I've got a couple "leave-in" type products of that brand that I haven't tested yet (ran out of warm weather bathing season last year.)
Nobody has responded much to your initial question about insurance. Which type? There's medical/mortality type for the horse and there's liability type for you. For medical/mortality you'll have to contact insurance companies for quotes, most of them don't put costs on-line. Regarding liability, I would think it depends on circumstances. For example, if you own your own home and your horse injures someone (even if they trespass on your property--check out attractive nuisance laws in your state) you might as well just sign over your savings account and the title to your house. If you don't own a home or have a savings account, they'll just attach your wages for the next billion years. Most homeowner policies don't even cover big dogs, much less horses, unless you specifically add them (for an additional cost, of course.) That said, I don't have either type. Which might be a stupid choice. For example, if I had medical insurance I would have made out big-time in the last couple years, but if I bought it now I probably wouldn't have a sick horse for the years. I haven't spent on liability insurance either, but rather have relied on other methods. Never underestimate the stupidity of other people. For example, we now have electrical wire on the outside of our wooden fencing after some lady was trying to stuff her toddler through the rails at Nicky. Just this past weekend, a young boy was lying on the ground on his stomach halfway into Nicky's pasture under both wooden and electric fences, with a dog no less. Nicky's blind as a bat but he likes to chase dogs, and in addition to being a stallion his blindness causes him to be a little spooky when things happen outside his normal conditions (like little boys doing stupid things.)
Another comment on vets... One thing I didn't realize when we got our first two horses is that you can have a vet check (by a vet you hire.) Ours was an auction situation so they did have coggins certificates and the vet hospital had a vet check them all out and they were dewormed, but.... one of them ended up dead within the first three months. And if I sound like I'm harping on costs/expenses I am. I came out fairly cheap on that one (around $2000) when you add up the initial cost of the horse, the vet bills, and the cost of disposal (that one was a real head twist... Before I bought, I had really not considered that I would have a dead horse on my hands and what to do with it.) Anyway, I think a vet check could save you some grief; I wish I had of known about it.