Davemcc is right about going out into the world and listening to speakers. You should listen to as many different models, from as many different brands, of as many different types (e.g., ribbons, horns, domes, whatever) as you can stand to listen to, before you buy. And you should listen with a variety of types of music, with which you are familiar. The speakers will affect the sound more than anything else you buy, so put most of your money into your speakers, and make sure you get ones you like.
Also, when some new feature or format comes out, you don't need to replace speakers, so putting enough money into them that you are satisfied with them tends to be a good investment in the future.
If it is going to be a surround system, ideally, the front three speakers will be identical (with possibly all speakers identical, except subwoofer), with the next best being a center from the same manufacturer that is "voice matched" to the front speakers. So buy the front center speaker at the same time as the front right and left speakers. Also, if you are going to get a subwoofer, your main speakers only need to go deep enough to mate well with a subwoofer, so that can significantly affect what your main speakers need to do to be satisfactory. Typically, one can save money on main speakers by getting bookshelf versions of the tower speakers one was going to get, and then put that extra money into a better subwoofer than one could otherwise afford, and then get deeper and/or better bass (assuming that one sets it up properly, which some people don't, as they set the subwoofer level too high for their movies, and then complain that it sounds boomy when playing two channel music straight, forgetting that of course it will sound boomy with music if one has set the subwoofer too high!). Or, instead, one can buy bookshelf speakers from a higher line for that same amount of money, thus getting better midbass on up.
I personally use identical bookshelf speakers (-3dB at 50Hz) all around for my surround system, which gives me perfect voice matching all around, and use two good subwoofers for the bass. I will never go back to not having identical speakers for all channels (other than subwoofer, of course).
As for the phono input, you either have to have a phono input, or a turntable with a built in phono preamp, or a separate phono preamp. It would be most convenient to have it built into your receiver, but it does not have to be that way, and it might not be cost effective, depending upon what other needs you have for a receiver.
