There is no app for OneDrive so no synchronisation there, but there is one for Dropbox which you could use to synchronise to a Dropbox account. But from what I saw it synchronises to a folder in the public share on the MCM, so you may have security questions over it (although that may be changeable in the settings, I didn’t look too deeply at it as it’s not functionality I need personally).
When you say giving access to your work computer, I presume you mean a PC that is on a different network from the MCM (presuming that the MCM will be on your home network?). You can enable remote access on the MCM, which will then allow users that you set up to having it access via the WD apps/programs which you can install on remote hardware (e.g. your work PC). Note that the access is via the app/program only, it will not let you do things like map a drive remotely to your MCM, nor can other programs (e.g. word, excel etc) directly access your MCM files (although they can open then through the WD app/program).
But basically if you allow the MCM user remote access, then they can access any file/share that they could if they were logged into the MCM locally (ie via a device on your home network). So you would have to ensure that the user that you set up/use for remote access only has the share access priviledges that you want.