Yes, you can share files with other users. They don't need to be DriveHQ users.
You can share different folders to different users; you can set different permissions for different users. And there is no limit on how many files / folders you can share.
All the features work with Internet Explorer; however, for optimized service, esp. if you need to share a lot of files, or use drag and drop, please install DriveHQ FileManager 3.5 client software.
You can easily share a folder by selecting a folder and then click on "Share" button.
The best way to share with a non-DriveHQ member is either to ask him sign up a free DriveHQ account, or upgrade your account to a group account and create a sub-account for him. You can also upgrade your account to a group account (for free) and create a sub-account for your user. To upgrade to a group account, just logon and click on My Account, then click on Group Account.