All three are great communities and Cary is expected to grow to 165000-175000 in total population. The addition of 540 in the Western Part of Wake County is going to add to the growth of Apex and surrounding areas.
You are a smart buyer to be aware of these things and try to figure them out before it is too late.
The question about Yates Store is a tricky one, but there is no doubt it will get busier as the roads begin to connect and commuters find different paths. What is your definition of busy? Do you have small children that you would need to be concerned with getting out to the area? If it does become busy, will there be a traffic light? These are all questions you may end up with, and until the growth happens there are no real clear answers.
Evans Farm is in a contained area, and some of the roads have already been upgraded. At the intersection of Okelly Chapel and NC55, there is a plan for a large shopping center so that will definitely cause in an increase in traffic in that area, not necessarily within the neighborhood, but it could affect your commute, but also positively affect your property values if shopping is convenient.
Of the three neighborhoods, Twin Lakes is definitely in the most established area, it is still growing and more shopping is being added, Airport Boulevard will connect through, which will provide easy access to I-40 and the airport and again add traffic, but again since so much is already built there, there is a limited amount of traffic that can be added.
I hope that information helps you.
Have you considered working with an agent? When buying a new home it can be particularly important that you have an agent representing your best interests. The sales representatives in the model homes work for the seller and any information you give them about motivation and income will be communicated to the builder when negotiating your contract.
If you have any questions or would like to meet to discuss your options please feel free to call me or email me directly.
I look forward to hearing from you soon,
I don't know if this helps but you might check out this link http://www.townofcary.org/Assets/Planning+Department/Maps/So
or the town of Cary's website which has many useful links to the town's plans. See link below.