In the process of buying Paradigm Studion 100 + CC 690 for center.
a- Not sure if a Denon AVR-4310 would be able to drive these
You may get all sorts of opinions on this. If you believe in science, then you could find the answer by working out the volume of your room, gathering up the Studio 100's specs such as impedance curve, phase angle curve, sensitivity etc., and finally, the SPL you wish to achieve.
The 4310's has been reviewed by the HT mag with lab measurements, so the outcome in your application should be quite predictable. Depending on your specific needs, the 4310 may be more than enough for your speakers or conversely, it may not be enough. The bottom line is, more is better. The 4310 has pre-outs so you have the option to try it out with and without the help of an external amp. If the amp makes enough difference for you then keep it.