The answers to your questions are:
I installed the external antenna kit, not the repeating antenna kit. When I purchased my external antenna kit, the repeating antenna kit was not available. I think the difference is that the external antenna kit is hard wired to the control panel. The repeater is a wireless connection to the control panel. Consider calling Pressure Pro and ask for their advice on what might work best for you.
Newmar did not prewire my coach for CB radio. All my CB radio components were purchased after market and installed by me. If you want to use the Newmar pre wired installation here is what you can do.
To determine if you want to use the Newmar prewired installation or not. The #1 thing to remember is satisfaction with your CB will be determined by the antenna and the antenna wire. They must be matched (ground plane or no ground plane) to each other and then tuned (SWR) to your radio and specific coach.
<LI>Call Newmar and determine if their installation is for a ground plane antenna or no ground plane antenna. If Newmar says ground plane, ask where the ground plane is located. If they say it is built into the roof, that is good. Ask what size is the gound plane built into the roof. If it is 6'X6' or more then you are okay. If Newmar says they use the metal frame as the ground plane, that ends the conversation. At least you will know what antenna wire (ground plane or no ground plane) Newmar used.
<LI>If you decide to use the Newmar wire, the small antenna they put on the roof will provide minimal satisfaction or dissatisfaction. Consider purchasing a larger antenna (length). The antenna should be top loaded. Purchase an antenna that is easily tuned. I prefer the Firestik antenna brand. The antenna must match the kind of wire (ground plane or no ground plane) Newmar put in your coach. The #1 thing to remember, when is comes to antennas is size matters. The top of my antenna is 14' 2" above the ground (4' antenna). Consider purchasing a medium duty antenna spring.
<LI>Assemble all the pieces, including the radio. FYI, the radio does not care about all the above mentioned items. The radio just needs an antenna and antenna wire that are matched to each other.
<LI>Now the complete installation needs to be tuned to your specific coach. You will need an SWR meter. Radio Shack sells them if you can not borrow one. One wants the SWR reading as low as possible and the same on channel 1 and 40. The reading must be under 3 or you should see a radio shop to determine what is wrong. To tune the antenna, move the antenna tuning device toward the channel with the lowest reading. Think of channel 1 as the bottom and channel 40 as the top of the antenna. If the SWR reading, on channel 1 is lower than channel 40, move the tuning screw down to shorten the antenna. Move in small increments. Start with two turns, recheck and go from there.
<LI>If you decide not to use the Newmar prewired setup, consider purchasing a Firestik no ground plane antenna kit. Click Firestik Antenna Company
and then click on products. The kit in my coach is LG4-M2-B. For a picture of the antenna, click Antenna Picture
.[/list]If you find there is a lot of background noise, when the coach is moving and there is no or very little noise when the engine is turned off, consider installing ferrite beads on the electrical wires for the radio and anything else that might produce background noise. I use Radio Shack part number 273-105.
Lastly I rigged up a way so the wife need not listen to the low class chatter on channel 19. I wear a head set that covers only my left ear. The headset is plugged into the external speaker connection.
Cell Phone Booster
I chose a cell phone booster that is wireless to the cellphone(s). The kit is from Digital Antenna DA4KSBR-50U. It is a 3 watt signal booster (repeater). The installation is unique to each coach (floor plan). All the work is running wire, and the usual voltage connections. Click these links for pictures:
Inside Coach Phone Pick Up Antenna
3 Watt Booster Behind Steering Column
Antenna Wire Routed Through Rear Cap
Rear Roof Mounted Antenna
I installed a switch in the dash (Newmar switch in a vacant switch location in the dash). This allows me to turn the booster on/off. This setup will make you very popular with your RV neighbors. The booster will handle hundreds of call at the same time. All one needs to do is be in line of sight of my front windows. It is interesting at rallies. I put outside sun shades on my windows. Before the end of the rally, there is almost always a congragation of people standing in the general area of the front of my coach, using their cell phones. They have no idea why they can make calls from this area. For me, I'm glad to help.
For any antenna wire that transmitts, never:
1. coil extra wire. Always loosely lay extra wire where ever possible.
2. change the length of the wire that comes with the kit.