[OldManEtwon]

1. Do I have to hire a builder to build my house or can I build it myself? Since I do not want to have a builder be able to salvage my house while I am offline and have his buddies raid it.

2. Can I build a base on water? Example the floor is level with the beach just that it goes into the water since I want to build a mall like thing but there is not a lot of land to do it.

[Astro]

1. Do I have to hire a builder to build my house or can I build it myself? Since I do not want to have a builder be able to salvage my house while I am offline and have his buddies raid it.

2. Can I build a base on water? Example the floor is level with the beach just that it goes into the water since I want to build a mall like thing but there is not a lot of land to do it.

Yes you can build it yourself and Yes