1. DOSLib - Is it shareware or a purchased application?
I'ts Open Source - about halfway the page of the link.
2. When I install newer versions of Autodesk Software, such as AutoCAD, the install is going to put the data under the user's profile. In my case, it's by the NT account. Where is this data placed on your installs?
Same place. But also - all corporate content like line types, hatch patterns and LISP apps (basically all the stuff that's copied to a users Windows Profile, but then more or less modified) are on a network share.
I don't modify deployment settings for the content, since that most likely will bite me one day. In the 'old' days (pre-2022 versions), I added the support path for the network share to the deployment, as the first in line:

L:\AutoCAD\Apps being the shared folder holding all LISP files, including acad.lsp. So when a user started AutoCAD for the first time, AutoCAD would look for acad.lsp and acaddoc.lsp etc. in the defined search paths. And it would pick up acad.lsp in that shared folder and execute it, load the correct profile, modify different paths etc.
Unfortunately, the new deployment method as of version 2022 doesn't have this option. The customizations I make for these new deployments are the Trusted Locations (the network share containing the corporate support files), Exclude the Start In and drawing folders , Load acad.lsp once at the start of the session and have the Express Tools installed. Since you can no longer alter the Search Paths in the deployment, I created a simple acad.lsp that's copied to the local Support folder (C:\Program Files\Autodesk\AutoCAD <version>\UserDataCache\Support) by the installation batch file. The simple acad.lsp is picked up when a user starts AutoCAD the first time; it changes the Support Paths and then restarts AutoCAD. The relaunched AutoCAD then picks up the corporate acad.lsp which in turn makes additional modifications and restarts AutoCAD again.
It's not elegant, but since it's a one-time action, I think it's acceptable. This is the local acad.lsp:
;;******************************************************************************
;;******************************************************************************
;;** **
;;** The local version of Acad.lsp is executed after starting AutoCAD **
;;** It changes the support paths and displays a message to restart. **
;;** **
;;******************************************************************************
;;******************************************************************************
(setvar "cmdecho" 0)
(princ "Execute ACAD.LSP - local version...")
;;------------------------------------------------------------------------------
;;-- Visual LISP --
;;------------------------------------------------------------------------------
(vl-load-com)
;;------------------------------------------------------------------------------
;;-- Set Options on tab 'Files' --
;;------------------------------------------------------------------------------
(setq acadsuppad "L:\\AutoCAD\\"
userprofile_path (getvar "RoamableRootPrefix")
support_paths (vla-get-files (vla-get-preferences (vlax-get-acad-object)))
old_suppaths (vla-get-supportpath support_paths)
)
(if (not (wcmatch (strcase old_suppaths) "*L:\\AutoCAD\\apps*"))
(progn
(vla-put-supportpath support_paths (strcat "L:\\AutoCAD\\apps;" old_suppaths ))
(setvar "TrustedPaths" (strcat acadsuppad "apps\\...;" acadsuppad "cot\\...;" acadsuppad "support\\...;" userprofile_path "support\\..."))
(alert "AutoCAD doesn't use the correct configuration.\n\nClick OK to close AutoCAD and then restart it.\nThe configuration will then be modified.")
(command "quit")
)) ;_ end of if
;;------------------------------------------------------------------------------
;;-- End acad.lsp --
;;------------------------------------------------------------------------------
(princ "\nLocal ACAD.LSP is processed.")
Path "L:\\AutoCAD\\" is the network share. The code also changes the trusted paths, since I didn't get them right in the deployment 🙂
edit: after the corporate acad.lsp is executed, the local support path is no longer first in line, so the local acad.lsp will not be executed subsequently.
As for question #3 - I'm not sure what the questions is?