Audio Systems: Old Kenwood Rcvr to use for surround sound

Question
I have an old Kenwood receiver which is one of the earlier dolby pro logic receivers (model #105VR).  I would like to utilize it for a surround sound system.  I notice that there are no analog (coax) or digital optical input ports, just RCA L&R inputs for each input device.  I'm wondering how just L&R stereo channel can carry the information for the 5 output channels (L&R, Central & L&R surround)?
Further, my satellite receiver only provides either HDMI or a single coax for audio out (which I'm assuming carries all 5 channels of info).  Can the coax be inserted into either L or R inputs of the receiver in order to provide all information for the 5 output channels, or might it be time to purchase a new receiver?
One last question should I decide to go that route.  I was interested in understanding how 'bi-amping' works in the event that I purchase a 7.1 receiver for 5 speakers.  My understanding is that you can use the 2 unused channels (typically the rear surround sound L&R) to drive the L&R main speakers even though they are already being driven by their respective channels.

Thanks for your help.

Answer
Let's make it simple:  The 105VR is an analog stereo receiver. It will not connect directly to any digital signals such as HDMI, coax or 5.1 or 7.1 digital undecoded signal paths.

If you obtain a surround decoder and bring out the 5.1 or 7.1 analog audio signals they can feed the stereo inputs on your receiver for the two main channels but you will need further amplification for the remaining channels.

Bi-amping is for the golden eared enthusiast who wants a speaker system driven by two separate amps; one to drive the low frequency driver (or sub) and the other to drive the upper frequency drivers (mid-range and/or tweeter).  The crossover system for bi-amping is much more straight forward and can provide big improvement in sound quality especially around the crossover region.

You might be better off obtaining a modern, uptodate surround receiver that accommodates hdmi and digital signals coming from your satellite system.

Hope this helps.