I do free samples. I don't think it cuts into my profit at all, in fact it increases my profits by making me sales. A lot of people won't spend $5 on a bar of soap unless they know they are going to like it. Face it, you can buy 8 bars of ivory on sale for around $5. If you are dealing with people who haven't experienced handcrafted soap, then they need a reason why. Samples show them why. A free sample this week can lead to an order next week, and many times more in the future.
As for what to bring with you to a wholesale acct, you bring your wholesale packet which would included your policies, paperwork, brochure, and a couple full size samples in the line you are promoting. Since you asked that question I'm going to suggest doing some searches on selling wholesale. There is a lot to consider and you need to be ready for. Some retailers require barcodes to be on your packaging. Do you know whether your labels will be with your brand or with theirs. Do you know your cost well enough to make sure you make a profit with wholesale prices? How much will your minimum order be?
Understand I am not saying you are or are not ready I just wanted to give you some questions to consider.