Coupling capacitors typically limit only the frequency response on the low-end of the spectrum.
With those 68k, 100pF is definitely the limiting factor (1/2piRC = 23.4kHz). If you want to keep the two feedback resistors 68k, then instead of 100pF I'd lower them to something more reasonable like 33pF. You just want to limit the bandwidth slightly to not allow for high frequency noise and spurious signal, but you do not want (nor need) to low pass filter the audio signal at 20kHz.
Regarding the Rop=68k: It seems your maximum gain of the preamp is over 70dB. That is way to high for this circuit (SNR will become bad with such gain). I think you should lower the Rop somewhat so the maximum gain will be about 60dB, not more.
The typical input gain preamp in a mixing console may provide a gain of about 10 to 50dB with the 40dB range tunable by the gain pot. If you want more than 50dB gain, you can always crank other pots on the mixing desk, to get additional 10-15dB more
The minimum gain is basically set by the gain of the differential amplifier (opamp) part of the circuit. However, 10dB minimum gain is too much to allow for a line level signal to be injected into the MIC input, hence why mixer desks always allow means for attenuation the input signal by 10 to 20dB. Typicaly, there is a switch "20dB PAD" on the input, or the more common way is to implement two types of connectors: XLR for MIC level and a JACK (called typically also TRS 1/4") that is wired so that it attenuates the signal whenever something is plugged in - typically, just resistors in series with the signal that form a voltage divider together with the input imepdance of the MIC amplifier (10-20kohm LINE input impedance).
Keep in mind that those LINE jacks are TRS (tip-ring-sleev, ie. "stereo" type in laymen terms), but are used to transfer also BALANCED signal. For stereo LINE signal you need two separate TRS jack inputs.
Typically, TIP is the HOT side (positive polarity), RING is COLD (negative) and sleeves the ground as is standard.
This configuration allows for plugging an UNBALANCED signal, using just a TS jack ("mono"), which shorts the COLD (negative) input to ground.
I would recommend you to really look for some mixing desk service manuals/schematics to get a better idea how do these operate internally.
I have never built a full diy mixing desk myself (if I would, I would do it in digital domain now, hihi - I like DSP stuff), but I would encourage to do it. I have only built several specialized blocks, for example a separate quad MIC preamp such as yours, to turn LINE level only inputs on my mixer to another four MIC inputs.
Even if it will not be very useful result for practical use, you will pretty much learn a lot of the stuff during the process, which is why I love electronics.