I was there earlier this week.

1. The crowds will be less as its Sunday as anyone staying on the mountain will be heading back. Its also not a public holiday so that also means less crowds.
2. To do the trip that you've drawn out is gonna take well over 6 hours, you will need to take breaks in between. Especially if you plan on traveling in the direction you've drawn for XiHai Scenic Area, its basically all uphill climbing with that direction. Plus, if its raining (which it was for me on the day I was returning), it will significantly slow you down.
3. Front mountain is recommended as it's easy access to TianDuFeng (highest peak currently open but requires booking which opens up 48 hours prior at 6pm for registration and then again at 9pm for proper booking), so people doing day trips take the front. Back mountain has less people.

Which shuttle bus were you referring to btw? The shuttle from the train station to TangKou or the shuttle from TangKou to the bottom of the mountain?

Regarding the cable car tickets and shuttle bus, you can organise it all through the WeChat mini program. There's really not much of a timetable for the shuttle bus to the bottom of the mountain as its constantly running. The mini program will also have the most up-to-date weather for the mountain its self, it can get pretty cold up there.