clearvision

Support confirmed forced archival is a new "feature" for cloud hosted sites with no options on what areas to archive.  Apparently this is undocumented and set to 3 years (1to5 is range).  Claim it is being looked at.  Not having advance notice of this change is in pretty poor form.
For sites with reference type forums (food, wine, books, travel, technical advice) this is pretty fatal as content over 5 years is no longer searched, and pretty useless.  We have low density forums with over 10 years of history and the content there is not time sensitive.

You would need to use the framework methods for storing and retrieving files.
$file = \IPS\File::create( "core_Theme", $filename, $fileData ); print $file->url; /** * Create File * * @param string $storageExtension Storage extension * @param string $filename Filename * @param string|null $data Data (set to null if you intend to use $filePath) * @param string|null $container Key to identify container for storage * @param boolean $isSafe This file is safe and doesn't require security checking * @param string|null $filePath Path to existing file on disk - Filesystem can move file without loading all of the contents into memory if this method is used * @param bool $obscure Controls if an md5 hash should be added to the filename * @return \IPS\File * @throws \DomainException * @throws \RuntimeException */ public static function create( $storageExtension, $filename, $data=NULL, $container=NULL, $isSafe=FALSE, $filePath=NULL, $obscure=TRUE )  

For you:  It takes a bit to get the categories, fields, templates and page sorted.  If you don't do a lot of customization and just use the standard templates once you get that sorted it is fairly easy.  There might be decent guides now, there were none when I started using the database.
For your users, pretty easy:

Just standard type fields to fill in.

You can copy the group and then just remove the permissions from the standard member group. Do a group promotion to the new group as a secondary group to give them the access.
And no, you need to do it with a group.

Plugins are not always available for what you need done or updated quickly.   If you code your own (cloud users don't have that option anymore) you still have to spend time developing it and maintaining it.  For cloud users you can't test plugins on a demo cloud site, so you have to go live and see what happens after each upgrade.  
A reasonable number of template edits seems no worse than a similar number of plugins to deal with.  You are told if there is a difference directly and can quickly fix only those that need it.  I use my own template "bits" if more than a single line of code so the edit is simply a single line easy to recognize using a template insert {template=""....}.
At one time I rolled my own plugin for template changes, but found maintaining it more difficult than just modifying the templates and had to carry a source license, even though main site is cloud hosted, to keep it up to date.

Support confirmed forced archival is a new "feature" for cloud hosted sites with no options on what areas to archive.  Apparently this is undocumented and set to 3 years (1to5 is range).  Claim it is being looked at.  Not having advance notice of this change is in pretty poor form.
For sites with reference type forums (food, wine, books, travel, technical advice) this is pretty fatal as content over 5 years is no longer searched, and pretty useless.  We have low density forums with over 10 years of history and the content there is not time sensitive.