Here are some answers to some of your questions.
For taxes in Colombia, you are considered a tax resident if/when you spend more than 183 days cumulative in-country in any 365 day period. When that happens, Colombia asserts the right to tax your world-wide income. Colombia's tax rates are a higher percentage than in the US, and start at lower income levels. Any income over about $15,000 USD/year will be subject to taxation. Nevertheless many expats find that with deductions, they end up paying little to no taxes and any taxes paid are offset by the lower cost of living.
See more topics about taxes here:
https://www.expat.com/forum/518-9-tax-in-colombia.html
And here:
https://en.wikipedia.org/wiki/Taxation_in_Colombia
On becoming a resident in Colombia:
https://www.google.com/search?q=become+ … p;ie=UTF-8
You need a verified income of at least 3 times the minimum monthly wage to be considered for residency. Currently the minimum monthly wage for 2019 is 828,116 COP, so three times that is 2,484,348 COP, or about 787 USD per month at the current exchange rate.
You can also find out about how to become a resident of Colombia doing this search:
https://www.google.com/search?q=colombi … p;ie=UTF-8
Most words, phrases and webpages in Spanish can be translated to passable English using Google Translate:
https://www.google.com/search?q=google+ … p;ie=UTF-8
The internet is available in all major cities but may be spotty in the smallest villages and rural areas. There are various providers, speeds are generally less than what is available in the US, but the cost is also usually less. Cell phone service is widely available via several carriers but due to the mountainous terrain there are many areas with poor or no service.
What's it like living in Colombia? For most it is a pleasant experience where your money goes further than it does in the developed world. The climate is generally not too hot nor too cold, depending mostly on the altitude of where you live. Personal services such as maids, home delivery, gardeners, etc. are cheaper, since labor is cheaper. Most amenities of the developed world are available, but not as widely and maybe not the same quality or quantity. The pleasant experience is enhanced by fluency in Spanish, the most widely spoken language in Colombia. Without Spanish you will have many difficulties and frustrations.
I also suggest you go here:
https://www.expat.com/forum/viewforum.php?id=518
...and in the "Search the Colombia forum" box on the right hand side, type in whatever key word(s) for topics you want to find out more about - there is a wealth of information on this site.