Getting Started - What to Order

I'll say a few things on general "stuff to order" for doing stuff with the Espruino..
Ebay is a great source for cheap breakout boards and common sensors. Prices including shipping are much lower than adafruit et al. On the other hand, the best deals take the slow boat from china, and the ebay sellers are only good for the most common hobby electronics stuff.

If you want general stuff to play with - the DHT22 is a cheap temperature sensor, though they're pretty flakey. Some of them have wonky calibration curves (someone recently posted about one that halves humidity readings above 25.5C, for example), and they're generally flaky. But they're cheap. BMP180's are cheap and easy to use temperature and barometric pressure sensors (because your heating system needs to detect upcoming changes in weather, and proactively adjust the climate control, right?). If you have any devices in your home with 433 mhz remote control, some 433mhz tx/rx sets might be fun (at barely over $1 per set, who can argue? Maybe turn on auxiliary fans/heaters connected to remote control outlets in adverse weather conditions?). And, of course you probably want network connectivity of some sort, either a WizNET or CC3k, or that new ESP8266 (though the state of current support is still poor).

On the less-useful-for-your-project but still cool front, LDR's (light dependent resistors) for reacting to light, stuff with WS2812B LEDs for colorful lights, if the desire for such strikes you, are readily available.

There are some proper full-color LCDs available that the Espruino supports, but they generally perform rather poorly at present. I'd consider one of the displays from Digole ( http://stores.ebay.com/digoledigitalsolu­tion/ ) for your remote control, as you can get great performance updating them, while the screen is still large enough to read.

If you don't have a selection of common components, snag a resistor assortment pack, some 1N4001 or 1N5817 diodes, and some 0.1uf ceramic caps (or a capacitor assortment).

I prefer to put male pin header on the Espruino, and everything else. That way I can use F-F jumpers for almost everything (the male dupont pins do not inspire much confidence, compared to the male pin header, though they seem to work okay), and it's easy to get a clip lead or probe onto a pin.
If you can get the good stackable headers with the long pins, those are really nice, because you can solder a little wire to the bottom of the pin, and still put a connector on the top. Unfortunately, the bad stackable headers outnumber the good, and are very hard to tell apart in pictures. The best sign is if the seller disparages the ones sold by other vendors. The bad ones and have flat (stamped) pins that bend easily, and don't make a reliable contact.

Regarding remote controls, if you use WiFi or Wired Ethernet for communication, you could use that for the remote control - have it serve a simple webpage permitting control, and then every web browser in the house is a remote control.

For switching the zone valves, the L298D seems excessive, unless you actually need to reverse the polarity - there are much cheaper options (ULN2003, et al) if you just need to switch DC on and off.