Re: stud spacing
If you do decide to go with 24 inch spacing you might consider installing your drywall vertically instead of horizontally.
Installed horizontally the butt seams will have more chance of cracking since there is less rigidity with the increased spacing .... unless you install horizontal blocking.
Otherwise you could use 19.2 inch spacing .... the black diamond marking on a good tape measure .... which gives 5 spacings into an 8 foot run .... which will help the seams if the drywall is laid horizontal.
Just 2 cents.
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