Most of the important points have been covered. The protools v cubase argument will always continue just like the PC v Mac argument. The advice I would give is to find out what most of the people you will be working with use. For example most folk I know including the studios I use prefer Cubase so it makes more sense to use the same system. It is handy for getting help in areas you are not expert in.
Most of the home systems like Audacity and Reaper whilst having a fairly easy learning curve will not produce the pro results you may want. For radio ready you will most likely need the more expensive and difficult learning curve progs like Cubase and Protools or Logic. They are not cheap and also require high PC specs plus expensive hardware and interfaces etc. This gear can cost many thousands.....especially if you are going to use the many plugins and VST apps that most studios have as standard.
Whilst I have a pretty neat and hugely expensive home studio...I produce the important stuff in a pro studio relying on folk who are true experts to help me..

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