If I share a project file, I assume this works the same for the cloud or direct sharing.
What comes along for the ride with the shared file?
If I used a custom component in the project (.elementsdevpack / .elementspack), does it get shared?
If I used a custom HTML component, does it get shared?
Off you give link here to download a file all bits inside project get downloaded including custom components. I uploaded a project with an HTML component only to demonstrate an accordion with a picture attached to each accordion. have a look below
Thanks Paul. I could not think of a way to check (without uninstalling stuff) as I obviously already have the things I share. 
Gary i know sometimes people are doing work they don’t want the public to see so post on here and put that you’ve sent an email to support. But once you put it on here everyone can see but you can delete the link in you App and the download wont work even if you have put it on here. The link is to the Elements Cloud so if you remove the link is broken. If you just let me know all the brilliant things you’ve done before you remove them!
If you share a document, it will include the resources and the custom components you’ve created in the document. This makes Elements Documents easily shareable…
However, Dev Packs are not included in the project; they stay local to your machine and are intended for development, so they shouldn’t be shared.
This is where the Elements Store comes in. Dev Packs uploaded to the store, are encrypted and can be shared for free or for a price.
If they are used in a project file and the user doesn’t have the Pack installed, Elements will request it from the Store. If it’s free, it will download it. If it’s a paid pack and the user hasn’t purchased it, Elements will prompt the user to buy it.
One of our big goals for Elements (and the Store) was to solve the “missing plugin” issue that has plague Classic users and developers for many, many years.
There’s more preliminary info on the Elements Store available below 
Things are developing very FAST and we hope to be able to share much more about the store in the coming weeks.
Oh cool 