The plaintiff's attorney is "bluffing" (cleaned up version).
Your case is going to go through initial discovery, both of you will get competing experts in to "opine" (give their competing expert opinions) about the matter, and what the requisite duties were, whether the claimed defects were visible, etc. and the matter will settle - probably in mediation.
One of your attorney's primary goals for you is to try to help you keep the litigation costs as low as possible. (Unfortunately this means that they may not be writing back to you quite as quickly or as often as you like. Your attorney still has a duty to communicate with you, and if you truly aren't getting any communication from him or his office, you may need to start following up with letters (or more commonly emails - it is usually easier for your attorney to fire off a quick email response) asking for a status report - but keep in mind, your attorney's time is billed at an hourly rate, and unless you are a commercial client, you probably aren't going to be receiving monthly reports, etc. on your litigation (so have realistic expectations for communications).
One thing you can do to keep tabs on what is going on is to ask your lawyer (or his assistant) to have you "CCd" on letters that go out (keep in mind that a lot of communication is sent by email, and you may not get "CCd" on that - a lot of lawyers dislike sending their emails to clients for fear of it getting sent to the wrong person inadvertently (it happens a lot and a lawyer only has to get burned once to be "gunshy" about it). But if you are receiving copies of letters you should be able to get the "pulse" of your litigation.
You can also ask to have a meeting with your attorney (it sounds like this is fairly early in the litigation, it is worth sitting down with them for 30 minutes to get an idea of what they expect from the lawsuit, how to prepare, and they should be helping you get an idea of what documentation you should gather (expect something broad "everything associated with the sale").
I wish you the best with this matter - I am pleased you are confident in your attorney as a litigator (that is the more important issue here), but I am sorry that you find their communication skills with you to be lacking - I hope that the above helps put a little perspective on it (some of it is because they are very busy, but a lot of it is because they don't want your legal bill to be sky high).