Hi there,
I read your project and it is interesting. In fact, I have built several projects (Trading Bots) for Interactive Brokers in the past. I am an IT engineer and I work exclusively with Forex/Stocks related projects.
In your specific case, it is quite simple. Your idea to connect an Excel Macro through DDE to IB will surely work well, it is easy. But I tell you, if you use an stand-alone application and connect through their Socket API connection, it will work even better. With this you can create a more visual representation of your trading, strategies, activities, overall performance and statistics, all in one application which can be built in C#, Java, etc.
Of course, an standalone application is better for cases when you already have a well defined strategy and you want to automate this strategy, but in the case you want to experiment, create a small lab to find out new strategies, then the Excel solution will be better, because will allow you to change / modify parameters and behaviors with some basic Excel skills.
I have worked in small and very large projects with VBA for Excel and Interactive Brokers, so we will surely complete your project with no delay.
Anyhow, I let you decide what type of implementation you want to use. I am only widening your options to automate your project.
Well, I think that is all by now. If you have any question just let me know.
Regards,
Engr. Jhonny P.