Intercom cct:Any Error?

[lanre]

thanks for ur usual assistance on my project:"4 Link Intercom" at http://www.electronics-lab.com/projects/telephone/015/index.html.
Pls, I want to confirm d following:

a.) Is there any common connection between the two resistors labelled R9, R10 and the capacitor C4 at the DTMF input (I mean, are they connected at the point where the C4 input crosses the series R9/R10 combination)?

b.) Pin 8 of IC2(DTMF decoder) and Pin12 of IC3 are supposed to be grounded, but they're both connected to RS flip-flop, will that still work becos Only Pin 23 of IC3 which sholud be at logic 0 is grounded?

c.) Can I use a D-fli-flop with D-terminal connected to logic 0 (zero volt) in place of an RS flipflop since the only terminals I need are the R,S & Q in the diagram?

d.) Does the audio amplifier has an alternative such as using an inductor instead of it and if so how do I go about the connection to realise the same result for the above project?

Pls, help me out, am about concluding the project and I'll be very happy if it works!