I'll give this a stab.
Quote: "If I understand correctly is that I could have a new panel with a copper bus even though the feeder wires are aluminum?" Yes
Quote: "The way the existing setup is right now is there are #2 aluminum feeder wires going from the outside splice box directly to the meter. From the meter it goes into the panel. What I want to do is move and upgrade the whole service. The existing meter is located inside an enclosed patio therefore is not accessible to the utility company (unless someone is home). I was going to run a new feeder from the existing splice box and then run it to the new combination meter/main which will be located outside of the house. I want to replace the existing house panel and get it up to code being that it's approx. 40 years old." This 'feeder' you are talking about is just an extension of the service conductors....this is not a 'feeder', they are service entrance conductors.
Quote: " If the outside conduit would be run under the roof eave, does it have to be rigid conduit?" No - these service entrance conductors are 'outside the building', and as such many different types of raceways are permitted - I won't list them because these types of raceways are often limited by the serving utility or the local municipality...check with them [utility, local jurisdiction] to see what restrictions if any apply to this installation. See section 230.43 for a complete list of wiring methods allowed per the NEC.