Was It Handon or Rickard?

Borook tells you it's a bold conclusion, but the right one indeed. They both went out to kill Calder that day. Handon got to him first, and the person who Rickard saw in the distance he thought was Calder, but it was Handon!

Who murdered Calder Nettic?

Nettic was murdered in 3956 BBY by a colonist named Handon Guld after Nettic had an affair with his wife. An investigation into his death was carried out by Jedi Master Bolook and Revan.

What comes first KOTOR or swtor?

SWTOR does take place i believe 1500 years or so after KOTOR so it's not like you'll encounter characters you saw in KOTOR while playing SWTOR. I do recommend you play KOTOR 1 & 2 at some point, both are great games and much of the lore in them are brought over or mentioned in SWTOR. Hope this helps!