Yes, you need to have a reliable electrician look at this. This is not normal, and you could end up with a house fire. Something is not right here. I don't mean to be alarmist, but you should not be comfortable with this until your whole wiring system is inspected and possibly fixed: that means the breaker/fuse box and the sizing thereof, the type and adequacy of the wire gauges, the integrity of the connections between the wiring and all the receptacles, etc. Many home inspectors are not necessarily good at finding things hidden in walls or doing close inspections of the electrical system, so that doesn't make me comfortable.

There is a standard. A number of them actually, they just don't apply to proprietary residential smoke detectors. There's a 4-wire standard, for 24V-powered smoke detectors with a set of contacts to report to a central controller that smoke is detected. There is a 3-wire variant, which shares one of the contact terminals with one of the power terminals. There are newer digital serial standards. If I want to turn this guy's house into an office building, school, or factory, then there are definitely standards available. Unfortunately, they require him to buy stuff, something he seems very... uhh... well, did I mention I told him to buy a set of matching smoke detectors and he came back with only two, which don't match either the existing units or themselves??? It appears from my searching the internet that Firex (existing) simply connects the 9VDC supply to the interconnect wire to signal, and both of the new ones are Kidde, which is apparently the same company - whose website seems to indicate they are compatible... At this point, I'll believe it when I see it. Work resumes Monday.

I'll address a couple of the wiring-related questions and let others recommend brands. The usual wiring method is to supply power from a 15-amp circuit to the first detector in the daisy chain. (I say a 15-amp circuit because that means all the wiring can use #14 guage wire which is cheaper and easier to use than #12.) The first detector is wired for power using 14-2 and then 14-3 (black, white, red plus bare ground) is used to connect other detectors down the line. The black and white wires carry power from one smoke to the next--just like any other circuit--and the red wire is used as a control wire to propagate the signal so that if one detector goes off, they all sound. There are two schools of thought as to whether this should be a separate isolated circuit or whether it should be branched from another circuit with other loads on it. Some argue that it is better to tap a circuit with other loads (usually lighting) because if the circuit goes dead for any reason, occupants will notice that a light or other outlet isn't working. The other side takes the position that it should be a dedicated circuit so that it has the lowest chance of being out of order in the first place and that an electical short in, say, a lighting circuit won't disable the smoke detectors at the very time they are needed. (A dedicated circuit also allows for easy installation of a battery backup capacity for the "smokes" without having to power other loads. This is required in some jurisdictions.) The electrical code does not cover wiring of smoke detectors. However, fire codes sometimes do address the issue. In my area, and a number of cities across the country, smoke detectors must be on a dedicated circuit to meet fire code requirements. In other areas, it is considered "best practice" to tap from a circuit with other loads as long as the path cannot be switched on and off (except via the circuit breaker). The best way to answer this question is to check with the local AHJ, keeping in mind that it may be governed by the building or fire inspector rather than the electrical inspector.

look at where teh cable enters your house. the first splitter should be a 2 port and have 1 side feeding your TVs and one side feeding NOTHING but your cable modem. if it is a multi port splitter, then you should have it changed out to a 2 port setup as i just described. you will need a larger splitter after the first one for the TVs, but you do not want a bunch of loss in front of teh modem so in low signal cases you use 1 2 port splitter only before the modem. you can get bi directional amps, but they are pricey, though certainly WAY less than teh 20k the cable co wants. just to give you a detailed example of a layout, here is how my parent's house is wired: cable in feeds a 2 port splitter. 1 port goes directly to cable modem 1 port feeds a 30DB one way amp that feeds a 12 port splitter. this 12port feeds every room in teh house, and 1 additional amp that inturn feeds a 4 port splitter going to the sunroom and 2 rear bedrooms. yes, that is a lot of ports. the amps are there due to fact that with so many ports the signal goes to crap to teh tvs. figure it this way, a 2 port splitter will give just UNDER 1/2 the incoming signal strength to each port, with a little bit just flat out lost. a 3 port gives under 1/3 signal stregth to each port, and a 4 port gives under 1/4. and so on and so forth.