Gmax 1.5 XT not the +

First of all, thank you to stop by and read this post.
I've bought myself the Gmax 1.5XT (not the Gmax 1.5XT+). I write that because most of my search about the 1.5 XT only was not really successful. Most of my finding was about the 1.5XT + and it seem like that there are some difference with both of them. I'm hoping to find some answer here.

The current firmware is Marlin 1.1.0-RC8. I'm wandering if there is a place where I could download the most up to date firmware for the Gmax 1.5XT?

The person that I bought the printer told me to update the RAMPS 1.4 card for a newer one. I've looked over the web and found one RAMPS 1.6 card from BIGTREETECH (Link). Do you think it is worth the upgrade, or I can simply continue with the RAMP 1.4?

The last thing I've found out about it is a thermal runaway error during print. I've search for it, and it may be related to the Fan near the extruder pushing too much airs?

In hope that someone here have some answer for me. Big thank in advance.