Here is a link on how to edit the vmx file.
The exact entry would be
mks.allowCursorConstraining = "FALSE"
I would recommend installing Wacom drivers in both the host machine and the VM guest.
I understand it is a matter of personal preference and work flow/work habits, and maybe even desk size/layout in whether to connect the tablet to the VM directly or not. But connecting the tablet to the VM directly just makes your evaluation a bit easier as you don't have to worry about the settings of the host machine as the tablet is unusable outside the VM. The downside is therefore you can't use the tablet surface to move the mouse pointer on the host and and have to switch over to the physical mouse attached to the host. But if your primary use case is to draw on the Intuos tablet, you shouldn't be switching much between host and VM (unless you only have one monitor and need to refer to some document on the screen of the host).
Aside from what JBGoode mentioned about the processors, perhaps increasing memory availability would be of help, too. You have to treat the VM just as if it were a real physical machine when it comes to specification.