b) on Bittrex BLOCKS is still disabled. You can buy and sell but you can't transfer it to an address (or put BLOCKS into bittrex for that matter)
You can buy at the ITO price. You can not currently sell or transfer any Block to or from Bittrex during the ITO.
After the ITO is complete, if you bought Block on Bittrex, you will have 48 hours to sell them back at the ITO price if you so desire. During this 48 hour window, you can not transfer Block to or from Bittrex.
After the 48 hour sell back period, you can actively trade Block on Bittrex.