My 2¢ ( which is what it's worth) is to get an AppleTV instead of the airport to use with your AV receiver. You get HDMI to the receiver which in addition to sound gives you visual interface - and movie rentals. You can stream from most IOS devices.
Yes you should add your Bluray to the set up. A lot of people have 2 channel set ups for home theater/music systems. Consider making it a 2.1 system by adding a sub to take advantage of the low frequency output on the HT receiver. It separates out the low frequencies and send them to the subwoofer so that your bookshelf speakers can be freed up to handle the frequencies in their sweet spot.
I wouldn't go with computer speakers or powered monitors unless you already have them laying around. If you do use them they should be connected to the pre amp output of the receiver instead of to the speaker binding posts. This is a lower power output designed to send processed signals to an external amp. Most HT receivers can be used as pre amps.
There are a lot of speaker choices for this type of setup. I've used Axiom Audio M3's and if budget allows M22's with their EP 125 sub http://www.axiomaudio.com/bookshelf-speakers
. They are direct buy and a really good value. Start with 2.1 then when you want to grow add a matched center and then surrounds. This is exactly how I built my system - even down to the AppleTV except I use an old style one with an upgraded hard drive as my music server.
I also have an airport express using optical out to a little NuForce Dia dac/amp and two B&W LM1 speakers (I bought used for $175) in my bedroom system. You can read about it here http://www.head-fi.org/t/654778/book-shelf-speakers/15#post_9278992
. This might be a good budget solution for you as well.