What is the most vitamin C I should take per day?

Unsure. This has been debated for decades. I feel much better when the diet is high in vitamin c by true food like citrus. That is if possible.
ZERO. NONE. This is in normal food. There is NO BENEFIT from supplements, occasionally harm. You live in citrus country. Don't be a fool. Incidentally, all the vitamin C in US supplements today is imported from China to increase the profit margins of the vitamin pushers because it is cheaper. Almost none of it is checked for potency or purity.