1) Just about any wave editor would work fine. What you're going to do is to plug the cassette deck into the line-in on your soundcard and record the music as a wave. Then you'll burn the wave onto a CD (converting to cda format) with the software that came with your burner. So, what you need is some software that is capable of recording waves. Goldwave comes to mind but there are many others. I'd visit
http://www.harmony-central.com and check out thier software section.
2) I think that this should give you a good idea of how much space is required:
SamplesPerSecond * 60 * (BitDepth/8) = number of bytes per minute required for a mono wave file. So if your sample rate is 44.1khz and you're recording 16bit audio (this is CD quality) then you have 44,100 * 60 * (16/8) = 5292000 bytes or 5.292MB per minute of recording. If you're recording stereo then double that number -> 10.584MB per minute of recording. So 30 minutes of stereo music should run around 320 MB. Not too bad and probably less than you expected.
When you hear people talk about hard drive space being a huge factor with digital recording, they're talking about multi-track recording. Not recording pre-mixed songs from a tape deck into wave files. Think about it, if you're using your PC as a multitracker and your song is 5 minutes long and the sucker uses 10 mono tracks you're talking about 529MB of space for that one song even though the mixdown (combining all the waves into one listenable wave) will only be 52MB (stereo).
3) NO! MP3 is a lossy compression scheme. You cannot convert from wave to mp3 back to wave and expect the new wave to sound the same as the original. In fact it will sound exactly like the MP3 which won't be nearly as good.
There should be very little reason to worry about space if you have a CD burner. Store the waves on CD! You can even burn them to a CD in CD format and strip them back into wave format later without degrading the sound. There are many "CD rippers" out there on the net.
The benefit of MP3 comes into play primarily when transfering music. That is, it's a lot easier to download a 4MB MP3 than it is to download a 50MB wave. That's a considerable amount of savings and can be worth the degradation of sound quality.
If you're going to be playing your CD's in standard CD players, remember that you have to use CDR disks...not CDRW. Also, after you've stuck your audio tracks onto a CD, your software will ask you if you want to "close the session" or something similar. You must say yes or it won't work in your CD player.
Slackmaster 2000
