Plugs / Coolant / Filter for 100 hr

I have my first 100 hr engine inspection coming up, so I am about to make a purchase list. I have the Rotax branded Shell oil in stock but are looking for the latest recommendations AND best place to purchase the following:

Oil filter

Is this Rotax specific and should be purchased from Lockwood ? 

Spark plugs

I currently have NGK plugs that came with engine. If those are still the recommendation - read on the NGK site that threads are already treated from factory and that paste is not needed nor recommended. (https://ngksparkplugs.com/en/resources/5-things-you-should-know-about-spark-plugs)

What is a good gap setting for new plugs ?

Coolant   

I've heard so many recommendation - is there a consensus about a "Best practice" or "cant go wrong" for the 912 ?

While I fly in Arizona, often in 95F+ during summer, my engine runs cool, never approaching limits, so I am not looking for any help in that regard, just a durable cooler that is good for for the 912 system. 

Thanks a bunch, Tom 

P.s I fly a 2016 Revo Trike