In Poloniex, I deposit(Bitcoins -0.3BTC ) in my trading account. Then can I short sell say e.g BTC/ETH coins? if so how as in Sell section there are no ETH Balances. Also to what extent or Period I am allowed to hold loss position? I mean will they square off my position?
How can I fund myself – I mean can I deposit money in Poloniex? If Yes, then how to do it? then same questions for this type of trading as above please answer.
Once you have funded your Poloniex account you are able to do short selling as well. You can read more about margin trading and margin calls on their website. Regarding to specific questions about the platform I suggest you to ask their support, you can reach them here, they are the best position to help you on that.