1-wire is not a good idea for distances like accross a house. It is inherently single-ended and relatively high impedacne, so quite susceptible to noise. Everything might work fine until the water pump in your furnace kicks in, or you run a particular blender with a failed line filter, etc, etc.
I think CAN makes the most sense. The normal electrical interface for CAN, such as implemented by a MCP2551 and many other chips, is differential. This makes it quite good at noise immunity, certainly much better than 1-wire. At the distance of a normal house, you should be able to run the CAN bus at 500 kHz. That's also way faster than what 1-wire can do, although data rate is probably not a major issue if this network is limited to a few dozen sensors.
The end devices will basically require a micrcontroller each. However, those are small and cheap and low power nowadays. Instead of using bare sensors that talk directly over a 1-wire bus, you have a microcontroller that receives the raw sensor signal. The micro then sends the sensor data on over the CAN bus as defined by your protocol.
One advantage of using micros at each device is that you have much greater flexibility in chosing sensors. You are not limited by the small subset of sensors that have native 1-wire capability. Micros can read the voltage of analog signals, talk IIC, SPI, measure pulse widths, etc. If you have a micro, you can easily make your own sensor. It just needs to put out a voltage and the micro can do whatever interpretation is necessary. For example, making a light sensor would be as simple as tying a CdS cell and a resistor to a A/D input of the micro.
I would put the CAN lines, power, and ground all in one cable. Let that be your "bus". CAT5 cable would be fine for this because it is relatively cheap and readily available. Use one of the four twisted pairs for the CAN lines, and the other three for power/ground. One line of each of these pairs would be power and the other ground, for a total of 3 power wires and 3 ground wires. Get one good efficient DC power supply and have it drive the power for the whole CAN network. I'd probably use 24V DC for the power on the cable. Each device includes a small buck converter to make 5V and/or 3.3V to run the micro, sensors, and whatever other circuitry you might want on a node. Put the power supply near the middle of the bus to minimize the maximum distance from power to any node, and to minimize the maximum power current on any part of the cable.
You can use a normal silicon junction diode to measure the temperature. Even inexpensive ones like the proverbial 1N4148 will work. The trick is to bias the diode with a constant current source of one milliampere. You need to make sure that the constant currrent source itself is pretty stable with temperature or it will affect the accuracy of the diode temperature sensor.
Once biased in this manner the sensor diode will produce a forward voltage drop that is amazingly linear over a large range. Applications that I have designed worked over the range of -55C to +135C. The forward voltage drop decreases with increased temperature and so is what we call inversely proportional with temperature. The rate of change of the diode voltage is about 2.2mV per 1C.
It is generally necessary to provide for amplification of the diode voltage drop and provide some offset so that the range of temperatures involved can be read via an MCU's A/D converter. An opamp can work nicely for this part of the circuit. If it is necessary to calibrate the sensor circuit it can be done with two trimpots in the opamp circuit to adjust the gain and offset of the amplifier. Calibration can also be done in software of the MCU as well if you provide a straightforward way to save the scale and offset values of the calibration in something like an EEPROM of part of the MCU Flash memory.
The above approach can be a fun learning experience and should work well for you. The diode is fairly easy to mount at the temperature sensing location requiring just two active wires plus possibly a shield if it is an electrically noisy environment. An alternative you may want to consider instead could be to acquire a low cost IC temperature sensor. The old standard LM75A is available in easy to wire SO-8 package and can be connected on a remote cable of just four wires. You would connect the I2C bus connections of the IC to an MCU control board.
There is a slight challenge that needs to be dealt with for the remote mounting of a temperature sensor. The connecting wires can act as a thermally conductive heat sink on the temp sensor thus offset the temperature reading some. For a simple control system this can usually be "adjusted out" by setting the control setpoint down by an equivalent amount.
Best Answer
Neurofeedback doesn't push signals back into your brain - the feedback is you looking at the signal or hearing the noise that's created by reading the waves. No signals return from the hardware direct to your brain so you're perfectly safe with something like OpenEEG - the electrodes are entirely passive (apart from signal amplification, but still no transmission into your head).
I was semi-involved with electrodes for a fun project that wanted to measure electrical signals controlling muscles so they could turn a servo (bionic arm baby!). I didn't do the procurement but one of the other people in the group said he got a good deal on disposable electrodes from the internet. Most of the OpenEEG electrodes are not designed to be disposed, so their build quality is a bit better and (I think) doesn't require the yucky gel.
In general, the electrodes are thin silver plates with wires attached. That's pretty much it - just have two so you can create a differential signal. Be warned though: the primary problem we had was 60Hz interference from power lines. The electrode cable made a decent enough antenna to pick up all of the interference around. I suppose in India it will be 50Hz? I'm not sure and too lazy to read Wikipedia at the moment, but it required some filtering because the signals we wanted were in the millivolt range.
Good luck!