"How is it done and how is it applied in this day and age, if (for people like me) people don't have access to their own darkroom and printing facilities?"
Find out what you can from whoever develops your film: do they let you specify developer or development times? What methods do they use ? You'll have to adapt to them or find someone who will support your efforts.
"How is it done digitally or with being able to do your own developing and printing with negative and slide films?"
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