Distribution supply business

I'm in negotiations to acquire a small distribution supply company (janitorial and cleaning supplies) as a self funded searcher. Deal is just under $2M. I have a few questions: 1. What are the typical industry margins or multiples for a distribution. business? 2. Are there any specific due diligence areas to focus on, and who can I hire? 3. Is there a structure where I can incentivize the seller to stay on for an additional 6 months post close during the transition? Thanks.