bricks,brigalo and yeast!

[bangers]

I've started to see a few references to bricks so I'm assuming we are refering to 20,25ltr water containers.I just recently purchased one to store my boiled water in an found it fits in my fridge easily enough thus giving me my chilled water for any brew.Righto that being the case if I was to use this for secondary fermentation an store my cider in the fridge at a lower temp do I need an air lock since its secondary (I've just had my first crack at syphoning off using my other fermenter) any thoughts?
I've just bottled my second brew using a brigalow kit so far so good ! I made 18 ltrs got 25 740ml pet bottles
I used the kit plus coopers enchancer #2 3ltrs of Golden Circle apple juice (pres free of course)
1Kg red apples shredded and frozen(been advised that by freezing the apples it improves their flavour ) I placed the apples in a sterilised stocking (then froze) and found that it helps to reduce cloudiness.at testing stage flavour was pretty damm good!at botteling stage flavour had improved.wont look at until April if I can help it!
I am starting to build up my knowledge on hb as I go along and I'm starting to take on more challenging aspects of it so heres the yeast question how to salvage yeast after a brew is it worth wile sa the nearest decent hb store is at least 20k's from home,as a novice thats why I use the brigalow kits If I knew had to salvage the yeast I woul probably go for all juice ciders and cut out the kit completely