Calo Nord can appears on all four planets. It depends upon how many planets you have finished. IIRC the fight on Korriban was the toughest one (limited space resulting in a bad place for Force Jump, and Calo gets strong Sith to help him), the other planets are easier (on Kashyyyk, Carlo has just two or three Wookies as help. On Tattoine, four battle droids).
This game uses pointbuy, so how powerful you are depends only upon how wisely you design your character. In your case, it doesnt sound like you informed yourself what good builds are out there (poor choice of forcepowers, you're still neutral). Unfortunately, KotoR is kind of poorly balanced in some respects. Meaning a great build will make this game trivial, a poor build can make it quite hard.
The available builds are actually fairly easy and logical: either go full lightsaber, or go full force.
Full force means: coundrel 2/Consolar, Cha 14, Wis 16, boost to Wis 21, Lightside Mastery for Cha+3, use lightside only gear from Korriban for another +10 Wis, learn Healing, Speed (sometimes you need to run away), Wave, Choke, Valor, and then whatever. Congrats, you have a ***load of force points and a ton of powers to choose from, and really nobody can resist your powers anymore. Well ... at least not all the freaking time anymore. Some will still need multiple applications of Force Choke before it actually hits. Also, dont forget to Valor before you try Choke such really tough opponents.
Full lightsaber is easy, nobody can resist lightsabers anyway: max Str, Force Speed, Dualweapon, one out of Power Attack, Dueling, or Critical Strike. Get Heal and if you're DS also Lifetap. Maybe go Scoundrel7/Guardian for +4d6 Sneak Attacks on Force Jump and if your opponent is disabled.
You can also go more defensive (max Dex, Dueling etc), but the toughest opponents will hit through your defenses anyway, so thats really pointless.
Strictly avoid to spread yourself. Dont give yourself a little of this, a little of that. This leads to a build that cant do anything right. And especially avoid the darkside Consolar. They arent fun at all.