The 25 hr inspection is nothing regulatory / required by the FAA. It is stipulated by Rotax and should ideally be done by a mechanic with the proper iRMT certification for the 912iS. Having it done and documented properly is important for maintaining warranty eligability.
As a side note, Van's is now offering as an option, to have additional flight time flown off and have the inspection completed before the customer takes delivery. This is done by flying the aircraft 15 hrs and then an iRMT certified (in house) mechanic the inspection and sign-off (Rotax's requirement for the inspection is 25 hrsm + or - 10)
As for cowling protection.... there has already been a lot off good advice provided. One thing not covered is to never, ever, stand the cowls up on there aft edges for storage while removed (or let a mechanic do it). This is particularly important for the top cowl but good for habit development by doing so with the bottom as well. The cowls are very light, and the slightest breeze or bump will send the top cowl tipping onto its top.