I understand that you want to connect NI USRP 2954 to MATLAB. You must have either Communication Toolbox or Wireless Testbench. You also have to install Hardware Support Package of either of the two toolboxes. Details are below.
1) You can find that USRP NI 2954 series is a support hardware of USRP Support package.
See the link for details.
2) Go to the link below in order to understand how to configure your host computer for ethernet-based USRP connection because X310 is a Ethernet-based radio.
Configure Host Computer for Ethernet-Based USRP Radio Connection - MATLAB & Simulink (mathworks.com)
Below is a quote on why you need Ethernet cable.
The Ethernet connection is often referred to as a network connection. You can use either an integrated network interface card (NIC) with a Gigabit Ethernet cable or a USB 3.0 Gigabit Ethernet adapter dongle. This connection is necessary for transmitting data, such as an FPGA or firmware image, from the host computer to the radio hardware. It is also necessary for sending and receiving signals to and from the radio hardware.
3) Perhaps I need more information on "Or I'd like to know if I need other devices such as cables and antennas separately". However, basically, you need antennas in order to transmit/receive radio signals in order to run communication processes.
