Will the bookmarks on the factory browser disappear?
The bookmarks should be stored in the cloud, do you have a desktop PC running Chrome? If you sign in as the same user you should be able to see the bookmarks there.
Edit: Oh, you did say the factory browser. Assuming it’s not a Nexus, this probably isn’t Chrome.
I believe apps I’ve bought already will download automatically from the store?
When you first turned the device on it’ll have asked if you wanted this behaviour. Failing that, the Play store has a “My Apps” section, this will have a list of everything you’ve installed, in chronological order. So it’s usually easy to figure it out.
Have a quick peep at https://www.google.co.uk/contacts/ to ensure it’s backed your contacts up. If not you can toggle this behaviour on the phone.