For the smaller creatures that you might trap any Duke brand size 1 or 1.5 will work just fine. The same with Victors and Sleepy Creeks.
When you frequent American trappers' message boards you will often find trappers discussing various modifications for traps. This will not pertain to you. None of the animals you will be trapping require such measures.
Also you may want to consider going with body gripping traps made by the above mentioned manufacturers in the sizes of 110 and 55.