Newbie questions: timers as counters, RTC access and DNS alternatives.

Espruino doesn't generally expose hardware at that level (it differs too much from platform to platform to come up with a useful API). However you can look at the chip's datasheet and can then use peek32 and poke32 to mess around with the actual hardware and configure it exactly as you want.

On ESP32 that might be harder though since you're working under an RTOS, which will definitely want control of some of the peripherals.

Really there is no way to change the WiFi DNS name when connected as client?

There is on the Espruino WiFi board and ESP8266 (Wifi.setHostName()) - I just don't believe it has been implemented for ESP32 yet.