A.) I believe my soundcard has duplex audio. It is a realtek AC'97 card.
Looks like that's the On-Board soundcard that came with your computer. It has very small ports in the back 'stereo jacks for audio'.
Not very good for music production. I suggest you get an actual Audio Interface maybe something USB powered with 1/4 ins and outs and a Mic Pre (big black plug with three holes).
Until then...
The Mixer is all you need for now. You should have Audio INS and Outs on that soundcard's back. You plug the OUTS from your Realtek soundcard into the MIXER Tape RTN (Tape Return) or AUX RTNS (Auxillary INs) or Monitor IN. I couldn't see the surface of that mixer in any picture so I can't tell what the ports are called. The concept is to bring audio INTO the mixer for
listening purposes only. Every mixer does this.
The MIC goes into its normal slot and an Audio OUT goes into the RealTeks INS to record the signal coming from the mixer (the rapper's voice).
Troubleshooting consists of you doing
one thing correctly at a time.
You plug the headphones into the mixer and press play in AA and make sure you can hear the music.
Keep checking connections until that works! You plug the mic into the mixer and record yourself in AA. See that you recorded ONLY your voice and not your voice AND the music.
Check/change the ports and see where AA is entering the mixer.
There are settings to control what the MIXER sends out and monitors.
Sometimes called CNTRL RM (Control Room) you might have to check all of these until you find the right combination to make this all work.
Usually you can choose to have the headphones monitor the AUX returns or and Main out so he hears himself and the music. The Tape OUT or Tape REC is usually what you want to send OUT to the REALtek INS. MAIN OUTS usually goes to the speakers.
The bad news is that you'll have to use a bunch of adapters (Realtek stereo? to RCA etc) to run your audio into a budget soundcard. Again, a better idea is to get a solid Audio Interface to use these same concepts but with more options/flexibilty at a big jump in quality.
For now this will get you going until you can upgrade.
Pro Tools? Well, it's YOUR studio. You should be able to record properly no matter what. Use the sequencer that you like. Any DAW can be used to make a hot beat/record. Choose yours visually- you'll be staring at it for hours on end. If you're rocking AA then you're probably working with Audio files..chopping samples and such. Consider AA 3.0 since it hosts VSTis and supports modern Audio Interfaces (some new boxes don't like the old AA 1.5).
An MC having the means to record himself is VERY important. Also, you don't want him in your studio 'working the kinks out'. So your studio (obviously) needs to be
better than his. Meaning better quality and/or a better workflow becasue all he has to do is focus on his verses/performance while YOU run the session and deal with all the technical niggles. So yes, he should get
something to record himself on. I doubt you're charging him for time in your studio at this point so your time is more valuable than ever.
Good Luck with this.