I am currently in my 3rd and final year of a Computers/Electonics Engineering Technology program (3 year diploma in a Canadian college, we dont have associates degrees in Canada, so this is probably equivalent). Most of what you said is correct but the basic premise thicker is better, is basically true but thats because of the insulation, and for data communications coaxial cable is far superior to twisted pair (telephone cable and ethernet cable) but Twisted Pair is used for practical consiterations mostly. As for colours never seen blue, but most cables here are black (not used by the cable company), white, or beige/skin tone (usually cable company installed). In my digital communications class this semester Cable and Phone netwroks were just covered. As for fibre optic usage in the phone and cable networks, two way cable netwroks would not exist without fibre optics, in fact here most of the fibre optic lines that are buried are owned by the cable company and leased by the phone company, this is called a Hybrid Fibre-Coaxial network, and the phone network most of the newer sections are most likely coaxial. Cable currently has a potential of close to 600Mhz of unused (not for basic cable) bandwidth for digital cable and internet, theoretically this is split between 120,000 potential subscribers, but in practice in my area less than 100 houses (in my case probably around 50 houses), thats about 200MHz downstream thats shared and 37MHz upstreamed shared. Compare that to 1MHz up and down stream for DSL unshared, now when you calculate the bit rate you see a considerable difference in speeds and potential speeds, whenty eh day comes cable is no longer shared, basically a dedicated fibre connection, you will have hundreds of Mbits/s speeds available. DSL will never reach this without a bandwidth increase over and above the already expanded 1MHz (telephone line is 4KHz as human voice has a bandwidth of 4KHz). But by that time the voice network may not exist, and for that matter the cable netwrok may not exist by the time it would be capable of those suggested speeds.
Just so everyone knows neither cable or DSL is really digital, especially DSL, its just more advanced dial up modem technology with expanded bandwidth. And cable is utilizing unused analog bandwidth not used by basic cable. DSL still has analog to digital conversion (which creates possible errors) once it gets to the public switched telephone network, I do not believe cable has an analog to digital conversion in the same manner (as it is only modulated and demodulated not converted back and forth so no errors).
Sorry for the long technical eplanation. But it may help even those with a very basic understanding.