Have converted almost all my PRG MR pts to 100K Avios miles, so any help from those with "head" knowledge about the following appreciated: (US passport)

1. By visiting IPC first, I avoid Chile $131 visa?
2. By visiting COR or SLA first, I avoid Argentina $140 visa?
3. Any strategies to avoid/reduce Brazil or Bolivia visa fees?
4. What are Ecuador, Colombia, Peru, Venezuela fees-taxes; any strategies to avoid-reduce those?

All my travel is by air & all my stops are 3-4 day stock photography urban explorations in airports' cities. Thanks in advance!