1. Who do I use? Farm Bureau: both coverage for tractor, select implements (I insure stuff such as my chipper but not the 90 year old root rake that looks like a high school welding project), AND on/off premises liability.
2. Aside from a few products inapplicable to this discussion such as Federal flood, ocean marine, etc. insurance coverages vary quite a bit from state to state, particularly for items such as equipment which is quite often insured on forms that aren’t even as “standard” as the ISO Homeowner forms used by many states.
This is a state by state question, not a national or international question. You really need advice from an agent in your state who is experienced insuring equipment and who has a good understanding what you’re doing with it (business, personal, some of both) and where (restricted to a single premises, a couple of specific premises, or a wide variety of places.) Not saying you need to insure everything you have to the maximum possible, but you should have a good understanding of your coverage before you have a claim, not after.
With all respect to others here, if you get a specific answer regarding coverages from someone here, I suggest taking it with a grain, or maybe a tablespoon, of salt unless they reside in the same state where you reside and use their equipment in the same manner you use yours, or are a competent insurance professional in your state.