As long as you can comply with the regular income requirements, which I think mean an income of around $2000 a month ( but this needs to be checked) you can easily get a retirement visa, and a US renter of an apartment I own, is presently in the process of doing it. The metro system is good and cheap $1.50 for any distance, and there are long term rentals available at whatever level you want. Foreign pensions are not taxable here. Let me know if you have any questions. If you plan to be here in February, you need to remember that Santiago basically closes down for the month, if you want to get anything done, but on the plus side, I find it to be lovely, with little traffic. All the stores etc are open etc.

Have you considered Grenada?

In answer to your questions, proof of income, as long as it’s from legal sources and regular, is always able to be substantiated in one way or another. Immigration is used to retirees coming who have some kind of investment income or pension and are pleasant to deal with.
There is a metro system in Valparaiso, but as the city is very small compared with Santiago, the area covered is smaller. It is no cheaper to live there than Santiago.
What can anyone say about crime these days? Nowhere is immune. Everyday crime is more limited to cell phones, jewellery or items left on view in parked cars.
The climate in Chile can be whatever you want except tropical. The south gets lots of rain, and the north , basically nothing. The middle, ie Santiago and its environs, has what I find to be a very pleasant climate. Its mid winter now, with early morning temps about say 4c rising to around 20c, normally with cloudless days. Summer is hot , say 30-32, dropping to 15 at night. Spring and autumn are beautiful. We do get little rain, and what attracts my wife more than anything is the low humidity, as she suffers with arthritis.
The coast, say Valparaiso is humid, often has fog until midday , then sun until about 7pm.Winters tend to be grey and miserable
There are other smaller cities to choose from as well, say Talca which is a 3 hour train ride from Santiago if you need it, and is cheaper and quieter to live in. There really arent any tourist destinations as such, except for Vina del mar, which is full of tourists for Jan - end Feb, so should be avoided, as traffic is bad.