No.

Hm, any ideas on why it's saying I need this DLL when I hit this line?

Could not load file or assembly 'System.Windows.Forms, Version=4.0.0.0

I don't know.  I've been using the Sage COMAPI with Dotnet C# and VB for many years, and have never had that problem.  Here is a snippet:

AccpacSessionMgr sessionmgr = new AccpacSessionMgr(); // As New AccpacSessionMgr
Int32 sid = 0;

sessionmgr.AppID = "XY";
sessionmgr.ProgramName = "XY1000";
sessionmgr.AppVersion = "60A";
sessionmgr.CreateSession("", sid, out Program.Globals.session);
Program.Globals.a4wLink = Program.Globals.session.OpenDBLink(tagDBLinkTypeEnum.DBLINK_COMPANY, tagDBLinkFlagsEnum.DBLINK_FLG_READWRITE);
Program.Globals.a4wLinkRead = Program.Globals.session.OpenDBLink(tagDBLinkTypeEnum.DBLINK_COMPANY, tagDBLinkFlagsEnum.DBLINK_FLG_READONLY);

I don't know.  I've been using the Sage COMAPI with Dotnet C# and VB for many years, and have never had that problem.  Here is a snippet:

AccpacSessionMgr sessionmgr = new AccpacSessionMgr(); // As New AccpacSessionMgr
Int32 sid = 0;

sessionmgr.AppID = "XY";
sessionmgr.ProgramName = "XY1000";
sessionmgr.AppVersion = "60A";
sessionmgr.CreateSession("", sid, out Program.Globals.session);
Program.Globals.a4wLink = Program.Globals.session.OpenDBLink(tagDBLinkTypeEnum.DBLINK_COMPANY, tagDBLinkFlagsEnum.DBLINK_FLG_READWRITE);
Program.Globals.a4wLinkRead = Program.Globals.session.OpenDBLink(tagDBLinkTypeEnum.DBLINK_COMPANY, tagDBLinkFlagsEnum.DBLINK_FLG_READONLY);

Thanks. What is the best documentation you've found on this API? I've been using these articles, but assume there's something more detailed
smist08.wordpress.com/.../ 

That's all the documentation I know of.

Last question. Maybe I pulled the DLL's from the wrong spot. Where do you find the DLL's required? I found mine in C:\Windows\Microsoft.NET\assembly\GAC_32

I get all my DLLs from the RUNTIME folder.