Even better, if you can find out who the electrician or company was that installed/built the house you could probably locate the original plans.
BTW welcome to the forum Jeremian. You came to the right place to ask your questions.
The documented stuff here and forum users are a gold mine of information for your specific needs.
If you decide to DIY this endeavor consider the support you will get from the users on CT relating to what you want to do.
The above noted; you should be able to find a set of plans with the local provider of building permits. I have done this and the fee requested for the copy was minimal and well worth it.
You will most likely need to stick to the original plans unless you want to spend XX amount of monies to redo the electric for you home which will be very difficult and expensive to do right now being that the walls are up.
Yup; and if you don't really want to get that involved in doing a DIY then I would look to hire a Lutron subcontracted installer.
Personally if you have not agreed yet on a purchase price of the house I would include a retrofit update of regular electric and subtract that from the selling price of the house such that you utilize that monies saved for either the retrofit or the Lutron installation.
A guesstimate for a post electrical wiring would be an expensive endeavor to add new HV switches / conduit et al plus the cost any drywall work et al.
I am currently utilizing a Leviton HAI OPII panel (2). That said I have integrated audio and CCTV stuff on the OPII and it works well.