"These are our bottles."
Translation:To są nasze butelki.
You can also say 'Te butelki są nasze', where 'te' also translates to 'these' ('These bottles are ours').
The difference is that 'te' always describes a noun, while 'to' is an independent adverb. In the sentence, 'To są nasze butelki', 'to' is a subject and 'butelki' is the object.
Seems that it wouldn't. A "pocket flask" for alcohol is "manierka", and another common meaning of "flask", the one used in chemistry, is "kolba".
So "flaszka" would be used for a simple bottle, but (almost?) only if that bottle if a bottle of alcohol (most often vodka), and it's a colloquial word anyway.