JPope

The dimmers installed together with a Visual 1 controller are so old that they have never been tested with LED's, as dimmable LED's didn't exist back then. The best way to figure out whether they will work or not, is to buy one of the dimmable LED's you want and try.
Other than this, there aren't any know issues with switching to LED's.

I had a Visual 1 controller until 3 years ago. Rock solid. As I remember it, all of the RS232 adaptors I have used had built in driver support in Windows 7, 8 and 10. The issue is usually not the driver for windows ... the issue is getting the LK software running. I never had any problems with that.
That is correct.
Keep in mind that if you upgrade the controller then you will need to reprogram it. While the programming paradigm is the same (and looks very much the same), you cannot transfer the program from a Visual 1 controller to a Visual 2 or 3 controller.
Should you decide to upgrade your controller you will get:
Visual 2 Internet access Wireless IHC (pushbuttons, outlets, etc.) Visual 3 Everything from Visual 2 Ability to use the latest dimmers (which are the absolute best for LEDs) More CPU power in controller Controller is supported by manufacturer

It's been years since I last worked with Visual 1, so my memory might not be 100% correct.
Regarding the driver for the RS232 adapter. Use the one recommended by the adapter. The important part is that i creates a virtual COM: port that you can connect to using the Visual 1 software.
Once you have established connectivity, make a backup of the program in the controller.
 
While you are waiting for the adapter to arrive, Install the Visual 1 software and load the copy of the program you posted here. Then you can familiarize yourself with the software and program without needing to connect to the controller. As far as I remember, you can also test and simulate the program in the Visual 1 software without connection to the IHC controller. At least you can in Visual 2 and 3.

Hello
In a home I have bought recently, I have IHC controller version 1 based setup with wired input/output modules (no wireless).
I plan to change IHC controller version 1 to version 2.
As I understand, I should:
Power off the controller, Disconnect all input/output wires, Connect them to the same sockets in controller 2, Power the new controller on and start setup process in IHC Visual app. My question - when I will power the new controller, will it automatically recognize all input/output modules in IHC visual app or I have to enter them manually? 
What else should I know to make the migration safe and efficient? Any help will be appreciated