Ebay descriptions imply that you can connect directly to 5V Uno. An Ebay description is not always truthful.
Yes, voltage dividers will be fine. Series resistors would probably work too.
The TFT.h library is designed for the ST7735. The methods are not very convenient.
The Adafruit_ST7735 library is easier to use. And any graphics written for Adafruit_GFX is likely to work with all the other third party libraries.
David.