H2S was air cooled.
The Magnetron and rotating reflector were housed in the "bump" under the fuselage, part of the electronics were inside the box structure supporting the radome and cooled by heat disipation from airflow as well.
The display unit was mounted at the navigators position.
H2X that replaced it was the same.
Village Inn did not have any form of IFF capability when first issued to active duty squadrons.
The two circles on the front windscreen were not used for IR lamps, they can be seen on any of hundreds of photos of MkI,MkII, and MkIII along with the Canadian manufactured planes that were fitted or refitted with the larger MkIII type bomb aimers blister.
All these photos were taken in the years before Village Inn was introduced.
Off the top of my head I can't remember the purpose but it was not as mentioned above.
German reciever units.
FUG 221-A "ROSENDAAL-HALBE": Passive homing device by Siemens. This device was designed to recognize and intercept the signals of the "Monica", "ASV" antiship, "Rosendaal," and "Magic Box" tail-warning transmitters. It had a 100-km range and worked with 190 – 230 mHz frequencies. The "Rosendaal-Halbe" never entered mass production.
FUG 222 "PAUKE S": Telefunken aiming device. It worked with frequencies from 3250-3330 mHz with a range of 300 – 10,000 m. Vision range of 100 degrees horizontally and 20 degrees vertically. The device was connected to an electrical ReVi device and monitor. Only 3 apparatus were build.
FUG 226 NEULING IFF experimental device by Lorenz. Me 262A Wrk.Nr. 170056 was equipped with this ground-to-air and air-to-air IFF device together with the FuG 218 Neptun. FUG 227 "FLENSBURG" It was a passive homing device developed by Siemens. The Flensburg could detect from a distance of 65 Kms (45 miles) the emissions of the "Monica" tail-warning radars of the RAF bombers. Production of this set began in Spring of 1944. The Flensburg antennas were installed in both the wings: at the top and bottom panels of the starboard wing tip and in the leading edge of the port wing. When on 13.7.44 the Ju 88 G-1 of 7./NJG 2 felt under Allied hands its FuG 220 and 227 sets were rapidly examined and countermeasures developed against them. Three different Ausführung with many improvements were delivered for a total of 250 apparatus.
FUG 280 "KIEL": The Kiel was a passive IR vision detector developed by Zeiss. It operated using lead-sulphite photocells amplified in a vision screen. Its range was about 4000 m; the unit weighed only 42 kg. Only a few devices were built.
FuG 350 "NAXOS Z": The Naxos was a Telefunken passive homing device similar to the FuG 227 ("Flensburg"). It was developed during the Summer of 1943. Production began in the early months of 1944 and the device entered service together with the Flensburg and remained in use until the end of the war. Unlike the Flensburg, the Naxos detected the H2S ground mapping radar (as well as the H2X, AN APS 15) instead of the Monica tail warning radar. Models I, II, and III used frequencies 82 – 84 MHz; IV, V, VI, and VII, 91 – 116 MHz. Its range was as far as 50,000 m in its best Ausführung, 10,000 in its very first versions. In whole 25 series were developed being the "Z" series the most successful with 700 apparatus built alone from "Z" to "ZR" series! The "Naxos Z" were used in Ju 88 G's in combination with the covered Morgenstern antennae because its elements could be easily installed inside the wooden nose cone or inside teardrop-shaped covers. Tests with Naxos were also carried in single-engined Me109G's (NH+VZ, for example) housed under a plexiglass dome on the second panel just behind the radio antenna mast behind the canopy.
Source
SkyLighters
Prior to Village Inn and Monica was Fishpond, which was used from the H@S to the radion operators position, basically a radar return with the gain tuned to within 1,000 feet of the aircraft that would show airborne targets coming in from underneath the aircraft. Not very effective.