Alcoholic Ginger Beer Questions

I am a brewing nitwit so please bear with me as I have several questions.

2 Days ago I started this basic alcoholic ginger beer recipe. I have listed it below in full.

The only area I deviated from the recipe was in using Lalvin EC 1118 yeast because I didn't have Brewers Yeast. Firstly I wanted to ask whether this should change my expectations of how long the fermentation should take or whether this changes the likely ABV? I believe his particular strain of yeast is used for sparkling wines and champagnes usually.

Secondly, overnight I have noticed that the level of liquid in my brew has gone down by several inches. Is this simply a sign that fermentation is happening? I used 2 litre water bottles so the difference in liquid height seems significant.

Lastly I wondered whether I should release the pressure before placing the bottles in the fridge tonight?

Recipe:

Makes 2 litres



INGREDIENTS

¼ tsp brewer's yeast

225g caster sugar

1½-2 tbsp finely grated fresh root ginger

Juice of 1 lemon

1 good tbsp honey

METHOD



Add the yeast to the bottle* (see warning below). With a funnel, pour in the sugar.



Mix the grated ginger with the lemon juice and honey.



Pour the ginger mixture through the funnel into the bottle. Now fill the bottle about ¾ full with water, put the cap on and shake the bottle until all the sugar is dissolved.



Top up the bottle with water, leaving a 2.5cm gap at the top, to allow for production of gas. Cap the bottle tightly, then place it somewhere warm. Leave it for about 48 hours. Once the bottle feels very hard and has no give in it, your beer should be ready.



Place the bottle in the fridge for several hours to stop the yeast working. Once the beer is thoroughly chilled, pass it through a fine sieve and serve.



»»»use plastic bottles««

Different to the recipe I use, but grated ginger, lemon juice, sugar (200-300g in 2 litres) and yeast is pretty standard. The (traditional) "yeast" I use will be a bit different; it's not just yeast but a symbiotic culture with a bacteria. This will be a lot less vigorous than a champagne yeast.

I allow 5-6 days to ferment out before bottling with "priming" sugar. then 3-4 days before putting the bottles in fridge.

The only explanation for the falling liquid level in the bottle that I can give is that the bottle is severely bulging (and distending) sideways, in which case I would attempt to release some gas to be sure its not going to explode on you!

Not a lot of Ginger, you want an ounce or two of rinsed grated plump fresh ginger per litre imho, circa 750g-1kg per 5gallons..
buy from corner shops and dont pay silly supermarket prices for root ginger, and for an extra fiery kick consider adding a fraction of a measure of chilli pepper,
fwiw 1 tablespoon in 5 gallons is WAY TOO MUCH chilli, i read teaspoon and understood tablespoon DOH!!

alternatively look into starting a ginger plant, its simply a case of priming a jar with spoonfuls of yeast sugar and ginger for a week or so to build up a population of ginger tolerant yeast in a concentrated ginger liquor