I'm excited that you're excited about live trading! Great news on the IB account, too.

Talking about upcoming features is a bit tricky for us. As a startup, we've adopted a very nimble (agile?) process that optimizes for getting throughput, but isn't very good at predictability. As we mature as an organization our priorities will change, and we'll get more predictable. I'll share what I think are the likely features coming, but please understand that some of these are likely to get dropped and others added in.

• We are working on providing live trading through IB. This is our high-level goal and I'll be surprised if it changes. We are a few weeks away from doing our first trades using our system. That's a big milestone, of course.
  
• limit, stop, and stop limit orders will be supported in the IDE and backtesting soon.
  
• the ability to cancel orders is coming.
  
• you will be able to see your order "blotter" to see what orders are opened, canceled, etc.
  
• walkforward papertrading is coming - you will be able to run your algo using live data and see your performance as the day progresses.
  
• one special bonus that is really exciting, but I don't want to talk about it until I'm sure we can pull it off!
  

Neither can I wait to trade.

All the above seem very important so you cannot drop in order to support live trading.

What about trailing stops and trailing stop limits. I would consider them among the most important order types.

Another very important feature is to modify an order rather than cancel and resubmit.

This reduces latency and the old order is live until modified. In cancel and resubmit there will be a short window when there will be no order or two active orders if you try to play safe.

Also you will have to support FX and futures. This is the most viable asset class for retail day traders. And also options.

If you support options we need to get the option / future chain by providing the underlier SID and expiration. Also provide functionality to get options expiring in n week from now, n months from now, etc.

Also ATM price. ATM + n levels.

Also get the security info on which these criterias pass. E.g. Info of option with 2 month from now expiration with strike at current ATM + 1 level with underlier QQQ. Info will have strike, expiration, underlier, etc.