i can play guitar and was thinking of buying bass, some questions

1. do i need a bass amp, or will the one i have for guitar do?

2. ive heard some necks are shorter, should i avoid these (are they "for kids"?)

3. i noticed the strings are the same, so that means same notes, same scales, etc right?

4. is it "easier" than guitar?

5. any recommendations on what to get? under $200