New to civil programming - way forward transitioning from VBA to using SDK

Hi,

Over the last 5 years or so I've been using VBA to help us automate and standardise some of our processes, however I see that there is limited functionality/access for VBA in ORD; there seems to be a push to move toward using the SDK?

If that's correct, I just wanted to know what the best way forward is to transition from VBA to using the SDK:
1. Is C# or C++ the preferred language (I'd need to start learning a new language). In our company we have both divisions that use both Bentley and Autodesk platforms for design so it would be good to go the route that could possibly service both platforms.
2. Is Visual Studio the only IDE that is supported? Can I use visual studio Community? Ideally I'd like to test the waters in a free or open source environment first, and then motivate to purchase a licence for Visual Studio if that is the better development platform?
3. Do I or my company need to be a part of the BDN or is that only for commercial development?

Lastly, as an intermediate, self-taught VBA user - how difficult is the transition? I know this is kind of like asking how long a piece of string is but it would be useful to hear others' stories that may be similar.

Thanks in advance for your help!

Chris