I know how you feel about he fizzling crackling sound. That usually means a speaker is malfunctioning. I have to replace the drivers speakers in the kick panel for that reason.
As for speakers most are designed to be compatible with factory stereos. If your replacing your head unit you will probably need a new harness so it plugs into the factory system. Are you having it installed professionally? I have heard that when you replace the factory radio that the 6 disk CD changer in the trunk will not function properly as it was only designed to work with the factory system. If you want to be certain it will fit in your car ask a certified installer. Most vehicles need a harness or mounting kit for aftermarket devices.
I personally like Alpine head units the best. They are a little expensive but they are worth it. Most now feature Blutooth compatibility as well as a jack for an iPod and USB drive. Are you thinking of replacing all your speakers at once?