DHCP

It looks fully configurable from this article:

Mavericks Server Admin: Provide IP addresses with DHCP

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Apple have sadly removed a lot of functionality from their server software over the years although they have dramatically removed a lot of the cost as well. So you are correct the Server.app does not let you delete a client lease from the list unlike the older Server Admin.

Turning the DHCP server function off and on may be a quick option but otherwise you may have to consider an alternative DHCP server. I believe the list of leases is stored on the Mac server at /private/var/db/dhcpd_leases hypothetically it maybe possible to stop the bootpd aka. DHCP server, edit this file, and restart it.

With regards to other functionality like defining Time Servers, this can be done but not via the GUI. You will need to hand edit the /etc/bootpd.plist file. As the name of the config file suggests Apple use the bootpd software as the underlying DHCP server but have hugely modified it compared to the original open-source version. You can find information about the DHCP options supported as standard by typing -

man bootpd

As mentioned functions like Time Server, LDAP server, NetInfo server (aka. WINS) are all built-in and you merely have to add them manually. Other custom DHCP option codes can also be defined for example to add support for a VoIP phone system however the format for doing this is not intuitive. In fact for custom DHCP option codes you ideally need to use a utility I wrote to help out.

See http://jelockwood.blogspot.co.uk/2013/06/dhcp-server-on-os-x-server.html

Note: I don't believe a Mac client would actually use the DHCP option for a Time Server but it will cost you nothing to try.

I have previously used this approach to add support for a VoIP system, currently use it to define a WPAD (Web Proxy Auto Discovery) address, and like you I am about to add Time Servers.

Note: Apple call WPAD - Auto Proxy Discovery.

Again back in the day of Snow Leopard Server Apple did provide a full-blown LPD print server for LPR clients, they also supported Windows clients via SMB printing as well.

With Apple's current server software there is no GUI to configure LPD/LPR printing and SMB printer sharing is completely gone even at the command line level.

As you yourself said it should be potentially possible to setup LPD/LPR via manual editing of config files in the command line environment.

For sharing a printer between Macs you do this in System Preferences. (This does not use LPD/LPR.)

apple.com/feedback

I have been requesting a lot of features to be added. Unfortunately the feature set has been adding slowly since Server.app v1.0

I'd like to see DHCP being more capable like you mentioned. I currently have it turned off and use my router for it.

I would also like to be able to use RADIUS for third party WAP. The technology is there, just no GUI to manage it.

Many "serious" users of Server would not consider using the built-in DHCP service for a different reason. That is, if the server crashes, DHCP service will be off until the Server is working again. So the entire Network is dead if the Server goes down.

For that reason alone, big users such as educational institutions prefer to have a separate "stunt box" doing DHCP. It may be combined with Firewall services.