If I fund 100% of a small business, how much of the company is mine and how much is my partners?

How much you put into a company out of your own pockets is irrelevant, this is something you need to get on paper ASAP, to prevent hardships, and headaches in the future. Go to a lawyer, have them create a contract stating how much of the company you own and how much your partner owns, and have it discussed, agreed upon, and signed by both parties. This will save you a lot of money and time in the future if the company ever goes under or if your partner decides to turn their back on you and take over the company and kick you to the curb. This happened to 2 of my businesses I ran with a family member, I had no documentation or nothing written in contract form, I come back from a training for 2 months and they completely took over the company and left me high and dry with not a single cent to my name.