Basic Software/Hardware Needs for Mac recording studio?, Need advice on cheap alternative for home recording Options

I have Adobe Premiere editing software and I want to utilize my instruments(Midi keyboard), Acoustic Guitar, Electric Guitar, Tascam 4-track, and Zoom effects processer(Midi Outlet), and microphone. My goal is to record original music and then use it in Premiere as a soundtrack. I also have a G4 Power Mac.
  What are the cheapest, most basic, and essential needs for such a poor artist(Software, Hardware, Etc...) to record on his computer? Any advice is good advice! Thanks

for asig non-midi recordings, I use SoundStudio. [http://www.felttip.com/products/soundstudio]
It is a really good and user-friendly recorder and editor.

[copied-and-pasted from documentation]
Features
Audio Recording:
• CD-quality recording (44.1kHz, 16-bit stereo)
• Records from any Sound Manager input device, including USB audio input
• Auto Start/Stop recording options for VOX-style and timed-length recording
• Disk-based recording
• AppleScript support for recording

Audio Editing:
• Waveform display window with zooming down to the sample level
• Standard cut/copy/paste editing, plus mixing
• Effects filters including Chorus, Flanger, Reverb, EQ, Compressor, Expander, Noise Gate
• More filters: Fade In and Out, Normalize, Volume
• Repair clicks and pops with the Interpolate filter
• Remove DC offsets and fix inverted signals
• Tone and noise generators
• Resample to different sample rates
• Adjust the pitch of the sound

File Formats:
• Apple AIFF with marker support
• CD Audio Track (requires QuickTime)
• Windows WAVE (.WAV)
• System 7 Sound
• Sound Designer II
• Dual-mono import/export
• QuickTime import/export (imports MP3s)
• Export as tab-delimited text

Needless to say, it's some pretty sweet stuff. The demo version only lasts 14 days nonregistered, so if you want to use it freely, budget your time or keep downloading it.
For MIDI recording, I don't know what to recommend. So far, I've just plugged my keyboard into the computer using the audio output jack, bcuz I can't find a suitable linkup between the two machines.