Still a newbie here... can I Summon/Set one monster and one Trap or Spell per each Main Phase? Or is the limit one monster per turn?

Again, I promise to buy and read the rule book soon... just haven't had time to go out and grab one....

Nope, sorry...the limit is one monster per turn. You can special summon as many monsters as you want, though...assuming you have room.

Always good to see new players.

You can only Normal Summon or Set one monster from your hand per turn. If you decide to do this during your Main Phase 1, then you cannot Normal Summon/Set during your Main Phase 2. If you do not perform the Normal Summon/Set during your Main Phase 1, then you can do it during your Main Phase 2.

Spell/Trap Cards, however, are a different story. You can Set or activate as many Spell or Trap Cards as you want, and you can do so in either of your Main Phases. Of course, keep in mind the 5-card limit of your Spell/Trap Card Zones.

Keep in mind that Trap Cards must be Set before activating them. Also, Trap Cards cannot be activated during the same turn they are Set (the Draw Phase of the opponent's turn is the earliest time you can activate a Trap Card set during your turn).

You are only aloud to Set, or Summon a Monster once per turn During your Main Phase, or Main Phase 2 unless an effect states otherwise. Any number of Trap's, or Spell's can be set in one turn according to hom many Spell/Trap Card Zones you have left unless an effect states otherwise.