Adding a switch to control a basement light
The switch you plan to add will work fine without a ground.  Do make sure there wasn't one tucked away in the lighting box, or trimmed back.  It is very rare not to have a ground in every cable unless it's a very old house.

If you want to comply with the strictest codes start by ripping out the existing light circuit, then run an all new circuit to the switch first, then to the light.

The conduit is not necessary to run down the wall if it's stapled properly to the inside of the stud cavity.

As for the outlet, you should branch it off of something grounded, or go to the effort of running a new circuit, so that you can have gfci in an unfinished basement space.

Or if it's something you won't use often, or doesn't have a grounding pin, consider those adapters that give you two ungrounded outlets and a light socket from one light socket, and an ungrounded extension cord.  Iirc, there are ones that have pull chains for the light too.