Personally, if you need to choose a switch ROS or SWOS based, I'd go with ROS.
Much more options and only 1 environment to learn.
I agree, I have admin’d a switch with SWOS for a while and that has learned me to never buy a SWOS only switch…
CRS328 will work, but it’s an overkill, it will require CapAx and cable run to it as well as labor to mount it.
There is another option then is to use CRS418 without WiFi and add CapAx.
Another concern I have with combo device is how to place wireless part of it into Caps mode
That's not really an issue if you stay within the same wifi technology ( don't go mixing wireless and wifi or it may become problematic).
Yeah, I learned that the hard way. I wish they used more distinct names like WiFi-AX
What happens if you system reset crs418 into CAPS mode
Will it simply bridge all interfaces
You don't need to put reset the router. And I don't know what would happen, or if it even support caps-mode.
You can enable CAPsMAN management in config on the router:
I doubt you can do that on crs device ?
Care to try and let us know ? 
If you reset device into whatever, then your config is toast anyway ... in that case "default" CAP mode (which might not be available on CRS as @holvoetn already noted) would be as bad as any other default config.
Other than that, I was commenting on your 3 options. As I already wrote, I'm skeptical when it comes to combos of (large) switches and APs in same box because that severely affects possibility to place both parts in most sensible places (switches and APs rarely make sense in the exactly same spot). As I already wrote, I'd go with option #2 (AP separate from switch) and I just suggested that using CRS328 instead of CRS112+CSS610 would make sense (if space and form factor allows).
Yes, it is very strange that they combined a WiFi version of this switch with the 19” case… one would expect it to be in the PC (passively cooled) case with external powersupply, like is the case with some other models.
I will give it a try.
If Mikrotik went so far to design it, manufacture it and deliver it to our market, I’ll just have to trust them. It has everything client needs and location wise it doesn’t get any better, it will go into the cabinet built for xray server and UPS with plenty of space for this switch and 24 port patch panel.
The only real concern is replacement down the road, so I’ll run an extra cable with one of the cameras for future Wap.
But if you are going to put the device inside a (metal) cabinet, you will likely need antenna extensions and supports for mounting the antennas outside the cabinet.