US Plumbing/Drainage codes

We manufacture a unique modular bathroom concealed within a bay window and factory built as a complete unit. Our unit is currently being assessed for licensing on the US market and I wish to familiarise myself with the general plumbing/drainage requirements in the US. (from comments Ive read regarding syphonic & venting problems,it appears progressive waste pipe sizing may be be smaller in the US).As a licensed Plumber & Drainer in Australia, I would appreciate any information regarding US plumbing regulations and local circumstances from an experienced plumbing contractor in the US ( Is there a National Code, or do individual states have their own regs etc …where can I source them..?) I would also appreciate any comments on the suitability or otherwise,of our unit to US housing styles (The Bay Window Ensuite was designed to overcome the problem of installing an ensuite to older inner suburban homes with the main bedroom on the front..it has been dubbed The Invisible Ensuite) Web Site..http:www.baywindow.com.au US.Patent No 5375380 Many thanks Ian Jones-Bay Window Ensuites