Esther E.

You'll need a custom application for v5 regardless, so you might be better served with creating a separate location in the ACP to upload this software and link it to a purchase.
Then, use a template hook to display the download in the client area when the user views the purchase. OR... have a separate, dedicated front-end controller that displays the user's own files. Much cleaner from a coding perspective.
 

Request granted. I've been working on this today.

That will be dealt with in UIExtensions. We're wrapping some things up on those before the blog entry, but it's coming.
We will be removing the block on base classes and you'll be able to add listeners to \IPS\Content\Item (or Comment or Review).

Custom applications will remain untouched. That includes files and data. For development environments, you would upgrade to v5 and then start with updating your files. It was mentioned above that this might be impractical, but the reality is that every file must be modified regardless; at the very least, the class needs to be renamed to remove the underscore.
In a live environment, your application would be disabled and locked until a new version is uploaded. Note that we did this when upgrading to 4.5 as well.
Plugins will be deleted completely, as the entire table is dropped. Your local files should still be present, though. 

Yes and yes. 

Yes, but the alternative would be to uninstall and have data loss. 
I figured the best solution is to leave everything in place so that when you create your application to replace the plugin, your installation can transfer those settings, etc to your app.

Custom applications will remain untouched. That includes files and data. For development environments, you would upgrade to v5 and then start with updating your files. It was mentioned above that this might be impractical, but the reality is that every file must be modified regardless; at the very least, the class needs to be renamed to remove the underscore.
In a live environment, your application would be disabled and locked until a new version is uploaded. Note that we did this when upgrading to 4.5 as well.
Plugins will be deleted completely, as the entire table is dropped. Your local files should still be present, though. 

Request granted. I've been working on this today.

Request granted. I've been working on this today.

Request granted. I've been working on this today.

Request granted. I've been working on this today.

Yes, it checks all of those things.
To clarify: It actually does NOT scan for used language strings. It scans for required/suggested language strings. So for example, it reads your acpmenu.json and makes sure that you have all the 'menu__' strings set up.

Yes, it checks all of those things.
To clarify: It actually does NOT scan for used language strings. It scans for required/suggested language strings. So for example, it reads your acpmenu.json and makes sure that you have all the 'menu__' strings set up.

Not at this time. 

We can look into the first one.
The second one is not on the road map at the moment. 

Technically the cart will accept any item, you'd just have to add the button on your end to add it to the cart.

Technically the cart will accept any item, you'd just have to add the button on your end to add it to the cart.

Technically the cart will accept any item, you'd just have to add the button on your end to add it to the cart.

Yes, it's fired on \IPS\nexus\Invoice\Item. you specify the item type you want to listen on, so in your case you'd create a listener on downloads\extensions\nexus\Item\File.

Probably with the new template hooks (which we haven't blogged about yet), but I confess I don't remember all the hook points offhand. 

Yes, it's fired on \IPS\nexus\Invoice\Item. you specify the item type you want to listen on, so in your case you'd create a listener on downloads\extensions\nexus\Item\File.

Some.
We added the following methods to the Member listeners:
onReact onUnreact onFollow onUnfollow As mentioned in previous comments on this entry, we allowed for listeners on base classes, like \IPS\Content\Item.
I'm not sure what other suggestions you're referring to regarding listeners. Was there something specific?

We're actually still adding a few things to the listeners, as there were some points that came up as we continue development. I do plan on posting a follow-up in the comments here when we're closer to finalizing those changes. Right now it looks like there may still be more, so I'd rather wait for a bit.

Of course. What I'm trying to do is get some answers as we're left in the limbo.

Some.
We added the following methods to the Member listeners:
onReact onUnreact onFollow onUnfollow As mentioned in previous comments on this entry, we allowed for listeners on base classes, like \IPS\Content\Item.
I'm not sure what other suggestions you're referring to regarding listeners. Was there something specific?