There are times when both a pre-amplifier and a distribution amplifier are both needed. My home is an example of this as a pre-amp can't do the job alone (yeah, a LOT of coax went into the house!). As it happens I use an extended boom 91XG, a mast-mounted PA18 plus one of our CDA-4 distribution amps in the basement. On one of the output legs, I had to install a third line amp. All this is to preserve two barely receivable stations, one of which my wife really, really wants (quilt shows on PBS) on a Tivo in one specific part of the house.
Given your proximity to your broadcast towers, I suspect you don't need any amplifier at all. Worst case, use an 8-way distribution amp.
As to your questions, Sara, I'll provide a little commentary. I don't know why the particular recommendations were made, but they're certainly valid. It's helpful to understand that the old adage of "There's more than one way to skin a cat" applies to antenna selection. For many locations, there are a number of potential solutions that will work.
1. The C4 is compact, the DB4e is not but it is quite a bit stronger once we get out of the lowest UHF channels. The DB4e is substantially less expensive as it costs much less to manufacture, package, and market. The C4's target customer is a person in a retail store (they hate large packaging!) that wants as much power as can packed into a small package and that yields an aesthetically small footprint once installed. The DB4e is not constrained by these factors. Obviously, this involves some compromises in the C4 as the guys who love huge, shiny aluminum sculptures will gleefully point out. In any event, an aluminum antenna can be painted with Krylon or Rustoleum and it won't affect reception as long as you don't get paint into anything critical like the connections for the coax. Please note that HOAs are powerless under the law to interfere with your antenna installation in most cases. See the FCC's OTARD rule for specifics at http://www.fcc.gov/guides/over-air-r...n-devices-rule
2. The U/V combiner will attenuate opposite band signals by more than 20 dB at each of the outputs so as to prevent the signals from one antenna from potentially interfering with the same-band signals from the other antenna. The C5, on UHF, behaves much like an omni-directional antenna and often works well as a single antenna for both UHF and high VHF. However, I'd only suggest it for short-medium range locations with uncomplicated signal paths. Based on your TVFool report, you would be a candidate for such an attempt with the C5. As an example, we only have one antenna on the roof our office in suburban St Louis (an all-UHF city), a C5 with a CPA19 feeding into an CDA-8 distribution amplifier.
3. The Winegard CC-7870 is nothing more than an old-school ferrite core transformer-type splitter (and not a very good one, at that) packaged to be used as either a splitter or combiner. I suspect it's been around for ages.
When using the C5 by itself for both UHF and VHF, do NOT install the EU385 CF combiner. Set if off to the side.
In the event that the C5 doesn't hit all your UHF stations reliably, I'd either back off to our C2v as I originally recommended to you by email last month or add the C2 (instead of the C4 or the DB4e) for UHF reception.