You will have to make it yourself.
Not much, awkward to carry but I was able to walk it up the stairs buy putting it on my back like a turtle shell. Maybe 70 pounds or so.
The units are rated and third party certified to 300lb load on the floors per ANSI Z124
Have one custom made and installed. Or buy one of the adjustable doors that will fit the opening size of your stall. Home Depot sells those.
I will suggest to check with your local store to see if they provide installation. You should be able to also find a shower door at the local store as well.
It rests on the front rail and the rear fiberglass/wood extension. No additional support required. I considered spraying some foam under the base for more support but not really necessary.
It doesn't include a door and not sure if they have one to fit it.
There is not one specifically for this unit, but there are various YouTube videos available. You can search Aquatic Install, but there are Many DIY videos and professions that will give you good information. I would also recommend pulling the Tech Data and installation instructions from the Aquatic website prior to your install to help you prep. Hope this helps.
No. If you remove the wood stops and door from the jamb it will be a tight squeeze if your door is 36 inches. There is no give. Most exterior jambs have stops that cannot be removed, better off with a 2 piece stall.