Are there any trustworthy and registered brokers for financial products (stocks, ETFs, maybe futures and options) that allow trading of Bitcoin as well?
http://www.hl.co.uk/shares/shares-search-results/b/bitcoin-investment-trust-npv Hargreaves Lansdown are a UK brokerage www.hl.co.uk
Look at the implied volatility at this exchange in Netherlands. https://www.deribit.com/main#/options they have futures as well. Bitfinex in Hong Kong was the leading exchange for people wanting to short bitcoin but they are having problems with their bank so you cannot get dollars out.