China DOS Union

I’d like to ask all the experts here a few questions:
1. Under pure DOS, what powerful, efficient replacement or enhanced commands/tools are there for MS-DOS internal and external commands or utilities that directly or indirectly support long filenames (indirect support means requiring support software, such as DOSLFN)? Where can I download them?
2. How do you drive several devices that use the same driver (for example, using VIDE-CDD.SYS to drive 3 IDE-interface CD-ROM drives)?
3. How can devices be automatically detected under pure DOS and the corresponding drivers installed (PCISCAN v1.10 may help solve this problem, but I don’t know how to deal with question 2 above)?

Also:
4. How can I find devices of the same type that have not been driven yet (for example, if there are 3 IDE-interface CD-ROM drives and 2 have been successfully driven with VIDE-CDD.SYS, how can I find the remaining 1 so that I can drive it with another driver)?
5. How can I find the smallest succeeding drive letter after C: (for example, if C: and D: are already in use, then the smallest succeeding drive letter is E?

1。There are downloads on this forum. Or go to DOS Paradise (starter site) and look there.
2。　3。　4。　Don't know those three.
5。You can go take a look at the Windows boot disk. See how it was done. Usually it uses the program findcd.exe and batch files, I think.

There are really quite a lot of DOS internal and external commands under DOSLFN that support long filenames, so let me list some:

Part One: non-DJGPP DOS programs:

Various commands in DOS 7.x, for example:
EDIT.COM
ATTRIB.EXE
MOVE.EXE
In COMMAND.COM:
COPY
MD/MKDIR
RD/RMDIR
CD/CHDIR
DIR
DEL/ERASE
REN/RENAME
etc...

Norton Commander 5.5
Volkov Commander 4.99
DOS Navigator 2.11
List Enhanced 2.4r/List Plus 9.6q
PKZIP 2.50
InfoZIP
ARJ 2.81
RAR 3.11
UNRAR 3.10
GetType 2.60
Universal Unpacker(UU) 2.13
FArc 1.24
Archive List and Date Stamp 0.92
Locate 1.30
ZSNES 1.36
NESTICLE 0.41
4DOS 7.50
MPXPLAY 1.47
OpenCP 2.60
QuickView Pro 2.50
Digital Sound System 3.01
Graphics Vision File Manager(GVFM)
Graphics Vision Editor(GVEDIT)
CMDEdit 3.20
Coig Change Directory(CCD)
WREN 1.0
XRD 3.03
XSET 5.47
Inkutils 1.53, such as MCD,DD, etc.
Most tools written by Horst Schaeffer, such as XFIND,VERSET, etc.
DOSIMG 1.81
UNDISK95
Disk Tools 1.83
LFNDir 1.02
Super DIR 6.19
NBASM 0.24.95
...
...
There are even more non-DJGPP programs that support long filenames.

Part Two: DJGPP DOS programs:

FreeCDP 1.1/2.1
RockNES 2.01
UPX 1.24
XPDF 2.01
Lynx
WGET 1.82
Qube
SEAL 2.0
SET's Editor 4.54
TDE
FileUtils 4.1
...
...
Note: there are also many more DJGPP programs, because the vast majority of DJGPP programs support long filenames.