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.

My jurisdiction requires incterconneted smokes in all bedrooms and in every other room except kitchens or bathrooms. Here they must be AC/DC and one of the ones in the living room area must be a combination smoke-CO. In most brands the CO detector will set off all of the smokes and they fell only one is needed. You can put in a separate CO, but it must be compatible with the smokes you install. There really is no savings by using separate units. $40 for a combination or $10 for smoke and $30 for a CO.
In the AC/DC I've liked using the BRK because the battery can be replaced via a door on the side. Many other brands require you to pull the detector down and replace the battery from the bottom. The trade price for these usually runs $10-$12 for an AC/DC smoke and $40 for a AC/DC combination smoke/CO.