Depends on how knowledgeable you think you are and if you think you can/should make the decision with/without them! I would definitely recommend it, though, because your trainer knows you and your riding style and can tell if you’re comparable. At my barn, the trainers pair the riders who want to lease up with lease horses because the trainers know the horses and the riders well enough to know if they would work well together and if the relationship would be beneficial to both parties.
Yes.... Your trainer can help you find the right horse right price right health and right skill.... Your trainer could save you a lot of headache also bring a vet and/or farrier just to be sure of good health don't want to hurt the horse and not know it!