Hi there. I’m a big Oman Air fan, although was hoping that one of the more experienced WY flyers would have popped up to tackle your very specific questions. But in the absence of any responses so far, I’ll give it my best - albeit incomplete - stab.

Regardless of whether there is any form of free stopover hotel programme in place by the date of your flight, I doubt very much that it would be available to you, given that your flights were booked as awards via Aeroplan. Such benefits are invariably provided for revenue ticket holders only (with all airlines). So I would adjust your strategy accordingly, and consider booking either the airside transit hotel at MCT or a Muscat hotel within easy reach of the airport (the Novotel would be a very respectable option for the latter). It’s true that your timings wouldn’t really allow the opportunity to see much of Muscat, and so a meal, followed by a decent night’s sleep is likely to be the only viable plan.

On the matter of the arrivals lounge : there is just a little info on this on the official WY website. I have no personal experience, but it will almost certainly be of good quality, if only because they tend not to do things on the cheap !

As for the First class lounge : I have a hunch (but could well be wrong !) that they provide access only a few hours or so ahead of the very limited number of flights which carry a First cabin. I would not bank on it being available throughout the night and it’s possible that you may be directed to the biz lounge where there are indeed a number of sleeping ‘cabins’ and good showers. The food in the biz lounge is very good & varied - but definitely not as good as the First lounge full à la carte waiter-service offering.

Will leave it at that for now, and hope the above is of some help (even if it doesn’t quite address your points as thoroughly as you may have hoped !)