Soldering irons / stations can serve many purposes over time so its actually one of those forever purchases that you want to invest in. I suggest you go with any of the temp controlled ones as they are even more versatile then fixed power ones. Just remember to grab a set of tips to match whatever manufacturer you go with. This discussion happened in another thread recently so no need to hash out what one is best as its another one of those personal preference things.
60/40 rosin core is best for electronics. That is the ratio of metals and has flux in the center to automatically clean your area for good joints. .032 inch diameter is for finer electronics and is pretty much industry standard or at least it was when I was working in manufacturing.
I used to get mine from work or from radio shack. But I am sure a quick search on Amazon will pull up a bunch of different results.