The factory engine sizes are a 2.5L four cylinder and a 4.0L six cylinder.
Yes, it will fit just fine.
No
Certainly, they are both YJ"s.
No they should not fit, 1990 is a YJ, and 1998 is a TJ
Yes, it should work, as long as the engines are the same
No.
No.
No.
No.
NO
yes, any top for an 1987-1995 can be switched out
Yes.