Direct download links to the add-ons below:
For player scale you can do findclientbyname("yourname").player.setplayerscale(0.15); in the console on your
own server to change your scale more and less than what it is for default, there may be add-ons to do better scaling but I can't remember their names.
I don't know about a headshot add-on, there are a few weapons which do it.
Health can be decreased with the add health event by default, use a minus before the number. such as on
On Activate > Player > Add Health > -15I don't know about a baseplate add-on to create buildable vehicles, but truce made an add-on for it,
topic link here.For the future, please use the add-on archives people have made after RTB's shutdown, links below:
swollow'stopic with all the add-ons linked by xalos