MT5 terminal & code against MT4 broker servers?

[tbuitendyk]

I've searched the forums for things like "mt4 mt5 compatibility", "mt4 terminal mt5 server", etc., and I am drawing blanks, so I'm going to ask what may seem to be a dumb question...

I'm starting a new EA project (the current version of my last one is pushing 15k lines of mq4 code), and was going to go completely outside of the MT environment for the engine and optimizing, writing this stuff from scratch in C# or C++ if C# turns out to be unsuitable.  My main reason for taking this approach are:

1. Optimization speed -- the new project is neural net based and due to massive crunching involved I am planning on using cloud computing to establish the error minima.  (Very important.)

2. Independence from the MT platform.  (Not as important.)

So, my idea was to use MT4 only for such tasks as interfacing for the engine to the market and building market tick-based data stores which the new design will require.  Then I noticed that my number one issue, optimization CPU resource usage, is potentially available natively in MT5 in terms of both multi core support (multi threading support?) and distributed computing.  Naturally these supported features change the picture somewhat for me.

My concerns and thoughts are as follows.  I would really appreciate insight into these areas before I commit to one architecture or another for the new project.

• If I build for MT5, will it even run against MT4 server platforms on the brokers?  As far as I can see the brokers are all still using MT4 (or at least the ones that I deal with.)
• If I build with MT5, will the virtual order thing (i.e., no hedging, FIFO only) be imposed on my code?
• If I take the MT5 option, will I be able to build *custom* optimization functionality that can be delegated to distributed computing resources?  (That is, init()-based customized optimization features, such as are implemented in my previous project.)

I hope these questions are not too naive.  I did look around and did not find much insight.  Probably due to information overload in these forums, maybe not due to it not being available.  Even if someone can help with links to pertinent articles that you are aware of that would be great too.  Thanks!

t.