I bought the same gun as my first 1911 and had the same ideas about upgrading it. My suggestion is to shoot it a lot before you jump in and start replacing parts, don't just replace them for the sake of doing it. Use the RIA to learn the platform and change out parts that you feel could use some work.
I've had mine for close to a year and have slightly more than 1000 rounds through it and the only thing I did to it that I had on my list was grips. I'm planning to change out the full lenght guide rod, but only because of preference.
I'm not saying you shouldn't do anything, but start throwing unneccesary parts at it and you'll quickly negate the lower price that probably made you pick the RIA in the first place.