I have used Lexol leather cleaner lots over the years, and in my experience it cleans well and drys without leaving any sign it was used. I always follow up with a leather conditioner after dry, so I don't think you would have any issues if you used it. I try to use the least amount possible...
My guess is that is the principal owed, and the rest is going to be interest you are going to pay on the balance owed at the end of the lease. Smarter people than me will likely clarify, but I'm on the forum now instead of doing the household projects I should be. ;)