Looking for some guidance on how/what I should spend my limited dollars on. This is my first sled. It runs good but want to be sure I'm looking it over properly before going for a long ride

Jets/carbs...should I pull them and clean them if it is running ok?
How to inspect track (52 spike)?
Shocks...How do I tell if they are blown?
My skiis are metal and pretty banged up...should I spend money on plastic ones? If so which type?
Need new runners...should I get 4" or 6" if I have a long track and 52 spikes?

Thanks for the help.

Garry...The Rookie for Granby, CT