A Wet / Dry filter will make it easier to add Chemicals, peat and anything else plus they are easy to clean and an Amazon tank needs slower moving water which is easy to control with a W/D.
A quick search in our DIY section will yield an array of filters you can make economically.
After that we would be happy to answer any othe rquestions you have, Amazon tanks are very interesting.
Depends if you want to have a planted tank or not. If planted: Use a canister (Eheim 2260/2262). If not planted, feel free to get a w/d for the reasons stated by Dr Joe.