You shouldn't need to have anything of your own except for your riding clothes
I'm a bit finiky, I know, but I wouldn't be happy about someone using their own kit on my horse, as I wouldn't know whether it had been used on another horse, and there is a risk (okay, it's a small risk
) of passing skin issues such as mites, infections and ringworm between horses. Not all owners are as fussy as me, though
I agree that the owner will probably tell you everything before you get the chance to ask it! When I had potential sharers come to see us, I had great long lists of things I needed to remember to say
Ask about the horse's routine, what is expected from you and don't forget to talk to the owner about what you expect from the share as well. Find out whether she is having a written agreement drawn up, and if not, do one yourself. Also check how any contribution is to be paid and see if you can do it by standing order, so that you have a record of payments. If she prefers cash, ask if she would be happy to give you a receipt. A friend of mine ended a share last year after things started to sour, and the owner claimed that she owed £150 in unpaid contributions. Unfortunately, my friend paid cash and there was no paper trail to prove it.
Also ask about any yard rules that need to be adhered to, what happens in the event of an accident (e.g. is there an accident book?) and how you would get hold of the owner if there was an emergency. Check whether there are any activites the the horse is not permitted to take part in, and whether the owner's insurance will cover you to ride, or if you need to take out a rider-only policy.
Ask about what happens if the horse needs the vet - does the owner cover the bill or do you split it? Are you permitted to call the vet or farrier directly if you think there is a problem, or do you have to go through the owner? Personally, I preferred my sharer to ring me first, and if she couldn't get hold of me to call the vet herself, as some injuries can look quite severe but are quite easily treated.
What is the procedure in the event that an emergency decision to PTS has to be made and the owner cannot be contacted? Some owners prefer the final decision to rest with the vet and the YO, but it's something that should be covered in your agreement.
That's everything I can think of right now... if I think of anything else, I'll come back!