If you provide accurate information I will help you with the items that you possess on your desk.
I am not going to waste my time until you have:
Compare the photos of the ER-TFT035-6 with the item on your desk.
Tell me what the differences are e.g. mounted components, pcb track layout, jumpers (solder-bridges)
Likewise for the ER-AS-ILI9341 pcb
Q1. You can access A0-A15 headers and the TX/RX/I2C header. Looks like 24 spare GPIO pins !!
Q6. The example works. Attach your sketch.
Regarding Q7, Q8, Q9. UTFT supports SSD1963_16. It does not support RA8875.
But you can read the UTFT docs yourself.
David.