You can easily get a bigger pump to get your water up to the second level in your home (say a taco 011). As far as the best piping setup, you can go to some of the OWB websites and they can give you some diagrams to help you get started and you can adapt them for what you have. Generally they recommend you putting your water heater first and hooking your furnace in series but it sounds like it would be hard to accomplish that with what you have. There are many factors that include pipe size, flow rate, and insulation that will effect your system that you'll need to look into. I think like Willie G. an important thing to do is run a heat loss calc on your house before you buy anything so you'll know just exactly how many btu's you'll need...
Check taco's website for pump sizing, they do a pretty good job of providing charts to show exactly what pump fits your application.