How do I display information about an interface controller?

Use the nicinfo command:

/usr/sbin/nicinfo device

This utility displays information about the given network interface connection, or all interfaces if you don't specify one. The information includes the number of packets transmitted and received, collisions, and other errors, as follows:

3COM (90xC) 10BASE-T/100BASE-TX Ethernet Controller
  Physical Node ID ................. 000103 E8433F
  Current Physical Node ID ......... 000103 E8433F
  Media Rate ....................... 10.00 Mb/s half-duplex UTP
  MTU .............................. 1514
  Lan .............................. 0
  I/O Port Range ................... 0xA800 -> 0xA87F
  Hardware Interrupt ............... 0x7
  Promiscuous ...................... Disabled
  Multicast ........................ Enabled

  Total Packets Txd OK ............. 1585370
  Total Packets Txd Bad ............ 9
  Total Packets Rxd OK ............. 11492102
  Total Rx Errors .................. 0

  Total Bytes Txd .................. 102023380
  Total Bytes Rxd .................. 2252658488

  Tx Collision Errors .............. 39598
  Tx Collisions Errors (aborted) ... 0
  Carrier Sense Lost on Tx ......... 0
  FIFO Underruns During Tx ......... 0
  Tx deferred ...................... 99673
  Out of Window Collisions ......... 0
  FIFO Overruns During Rx .......... 0
  Alignment errors ................. 0
  CRC errors ....................... 0.