Question 1: which. Question 2: that.
Answer:
In text, use numerals and “%.” Spell out the numeral and the word only if they begin the sentence. Where the percentage is less than 1%, add a decimal point and a zero.
Explanation:
English spelling is no more illogical than any of the linguistic conventions which have built up over time. In fact, if pronounced properly, English spelling is very straightforward and sounds as it looks (unlike Welsh or Gaelic). It does not rely on intonation, like Chinese or Japanese, and doesn't need accents, like French.
The sentence is missing two words, "will" and "a."
the corrected version would be:
In today’s blog post, I //will// teach you how to make //a// watermelon salad with feta and mint! With less than five ingredients, it’s a feast for the eyes and the palette.
