I think I have some basic premise down. As far as coax goes, I have a couple spools of RG-6. It's the same size used by Time Warner Cable. Is that the proper stuff.
On the issue of scanners.... I have had the pro43 right next to a Motorola hand held when I was moving around town. I noticed the scanner didn't recieve very well compared to the Motorola. I assumed it was the difference between $200 electronics and $2,000 elcetronics. Am I near the ball? Which scanners out there might be better? I tend to run accross them from time to time. If I know what to look for it may be worth it for the better reception.
RG-6 is fine. Scanners typically look for a 50 or 75 ohm input, and RG-6 has reasonable loss characteristics, especially if your run is less than 100 feet. Remember, for every 3dB loss in the cable you're losing *half* of your signal power! So it does matter when you're trying to receive weak signals.
The Motorola has much better front-end filters. Scanners are broadband by nature, since they cover a wide frequency range. Because of that, the scanner is more prone to desensitization, a phenonmenon you can't necessarily hear all the time. The Motorola could also have been more sensitive and/or had a better antenna. But rubber-duck antennas are universally poor, even though some are better than others.
You can still do well with a scanner. There is sufficient sensitivity there. One device that can improve airband reception is a front-end bandpass filter, such as this one:http://www.universal-radio.com/catalog/filters/0880.html
If you're really serious you can get one of these:http://www.dci.ca/html_commercial/photo_bandpass_vhf-4.htm
though they're not cheap. I have one of these at the Boston receiving site due to paging, two-way, and broadcast radio (FM band) interference.