No, you can not use current transformer to sense voltage. You need a voltage sense transformer, and trying to use current-sense transformer instead will be very bad. Your particular one can have inductance of up to just 8000 microhenries (as opposed to multiple henries power transformers), which means it will dissipate ~150000 watts (and instantly explode) when if you connect it across the mains.
If you are asking these kinds of questions, I highly recommend sticking up to pre-made power adapters and clamp-on current transformers (http://www.digikey.com/product-detail/en/CR3110-3000/582-1004-ND/1045160) which do not require you to mess with exposed high-voltage wiring at all.
Bunch of problems here.
You can't operate the LTSR15-NP like that - its 0V supply pin needs to be @ Ground potential to power its internals properly. Its output Vout is already at its Vref for 0-current, 2.5V +/-0.025V, so there's no need to do any shifting here. So IC1A & its C2/R5/R6 is not needed*.
LTSR15-NP also provides its Vref as an output, and you'd be well advised to use that as your system-wide Vref, all the way into the Arduino's Vref input pin. Let that be your reference voltage, because this is better than using the default 5V 'Vcc' suppy rail as your reference for analog measurements (because it changes, you'll get poor accuracy & even crappier long term repeatability).
The LTSR15-NP's Vout should therefore be voltage-divided 2:1 (e.g. R3=R4=10k) so that 0-amps = 1.25V, & full scale +ve = 2.5V, & full scale -ve = 0V.
IC2A is not acting as a buffer, merely as a level shifter to get your "0-volt crossing point" to be at half-Vcc. Again I'd instead use LTSR15-NP's Vref output into this level-shifter [edit:] through a 2:1 Vdivider, another pair of 10k, so that the 0-volt AC crossing point will be at 1.25V. Then i'd reuse the IC1A as an actual buffer in voltage-follower arrangement.
Then redo your R7/R8 calculations so that 150Vac (assuming you're on a 110/120Vac mains system) on TR1 primary results in no more than [edit:] 2.5Vpp, preferably a bit less. Then put some Schottky diodes on the R7/R8 divider node (before the Vfollower op-amp input) up to Vcc & down to Ground (i.e. both normally reverse-biased) to clamp spikes.
Also, you're only interested in 50/60Hz, so you'll want to filter out higher frequencies as much as possible (sampling theory, Nyquist etc), otherwise that noise (inherent in AC power distribution) is not only going to affect your measurements directly, but the noise above your sampling freq. will also fold back into your sampling frequency range of interest. Add caps on those two voltage-divider nodes with appropriately calculated RC timeconstants to start rolling off at, say, 100-200Hz. Do your resistor power calculations here!
Put 100nF (0.1uF) ceramic caps ('decoupling caps') across the power supply pins of all your chips [edit: and on the LTSR15-NP's Vref output].
I'm guessing (hoping) that IEC mains connector symbol is just a place-holder for your external wiring that puts the load in series with this, otherwise you'll only be measing the current/power of your own TR1 :).
Also, "as an exercise for the student", it might be interesting to do the V & I multiplication yourself in Arduino code, & compare it to the AD835's output :)
And all the applicable warnings for working with mains voltages apply - this is really dangerous stuff. If you've not done it before seek out help from someone who does. I'd strongly recommend working on this during the development phase with an Earth Leakage Circuit Breaker between you and the mains wall socket. Add a fuse. Always insulate all mains wiring so human contact is impossible or at least unlikely.
Best Answer
You could use a voltage divider, but it will probably be simpler and safer to use a step down transformer to scale the mains voltage down to something the Arduino ADC can read.
Make sure that you use an actual bare transformer that outputs an AC waveform and not a switching or rectifying power supply that outputs DC. You can use any transformer that brings the voltage down to a safe level (12 VAC is common for door bells) and then use one voltage divider to scale down to the Arduino's 5 volt peak-to-peak range and another voltage divider to center the output voltage in the middle of the Arduino's 0-5 Volt range.
Great info here..
http://openenergymonitor.org/emon/buildingblocks/measuring-voltage-with-an-acac-power-adapter
As for measuring current, the typical strategies include...
These are all used in practice, although current transformers are probably best for projects like yours because they are simple and do not require actually touching the high voltage wires.