openssh unix dev - Feb 2018 - Question about SSH and sftp

Hi team,

I think there are many information about my questions, but please let
me post in here.

I would like do the following things.

1. Allow one user to use sftp and set the limited access.
              ->To do this, add parameters in the sshd_config as follows.
                 Match User abcd
                 ChrrotDirectory /home/abcd
                ForceCommand internal-sftp

                 And also, do the comment out "Subsystem sftp
/usr/libexec/openssh/sftp-server

2. Not allowed access to server via SSH, but only one user can access
to the server via SSH.

In above case, the user "abcd" is allowed sftp access, but this user
can not login. This is OK, but the other user also can not log into
the server via SSH.  Actually, abcd user can not be changed to root.
But the other user can do.

Please let me know how I can configure like this.

Regards,