there are brush settings when using a tablet to set Opacity, Flow, width, etc. or allow the pen to control these! Buttons at the top of the bar when you have brushes slected there are buttons that turn on or off the controls by your pen/tablet!
as far as the transparency thing, Not aware of any tablet that is geared towards this, certainly doesn't mean there aren't any or you could possible Jerry Rig Something?
many thanks for your reply.
Would the brush settings be configured in photoshop or in the tablet's software?
Is there also a setting for smoothing out curves so that when creating curves for my lineart, they are more precise rather than hand drawn?
Yes - you can definitely use a pen tablet and have a constant thickness. You'll be able to adjust your brush settings using the Brush panel once your tablet is all set up. (If you can't see it, go to Window > Brush).
You can switch off pen sensitivity by change the Size Jitter Control dropdown to "Off".
A valuable button for you is the button I've highlighted in blue below. Clicking this button will disable using pen pressure with the brush size - when this is off, the size of your stroke will remain the size of the brush you have selected.
I personally create my linework by simply scanning in an image and "tracing" over it on a new layer in Photoshop. I usually drop down the transparency of the original image to make it easier to see my strokes. I have a very basic, cheap tablet and I find this method very easy.