Here are the corrections for each sentence:

1. **Correction:** "My parents bought me an iPad **which** I usually use to learn English."
*Explanation:* "whose" is incorrect here; "which" is appropriate for non-human subjects.

2. **Correction:** "I have a friend **who** is usually good at doing reading comprehension exercises."
*Explanation:* "which" should be replaced with "who," as it refers to a person.

3. **Correction:** "Most tourists spend some time browsing **the** local market, which usually offers unique cultural experiences."
*Explanation:* "at" should be changed to "the," and "offer" should be "offers" to match the singular subject "market."

4. **Correction:** "My brother wants to visit Kyoto, **which** has a rich culture and history he’s long heard about."
*Explanation:* "who" should be "which," and the sentence structure needs slight adjustment for clarity.

I hope this helps you improve your English!