There are not just 13 non-palindromic numbers. Most numbers are non-palindromic.
There are 90 palindromic numbers between 100 and 1000
No.
Nobody went out to create them: some numbers simply happen to be palindromic and others don't.
No.
777717711771817718817...
infinite
there are 10 palindromic numbers between 9000 and 10000 9009,9119,9229,9339,9449,9559,9669,9779,9889,9999!!!
As 20569.8 is not palindromic, any number that is like it must contain that property and similarly be non-palindromic, so no.
There are more 12-digit palindromic numbers than 11-digit palindromic numbers. This is because the number of possible 12-digit palindromic numbers is greater than the number of possible 11-digit palindromic numbers. In general, the number of palindromic numbers of length n is 9 * 10^((n-1)/2), so for 11-digit palindromic numbers, there are 9 * 10^5 = 900,000 possibilities, while for 12-digit palindromic numbers, there are 9 * 10^6 = 9,000,000 possibilities.
I guess that the smallest would be zero, if you don't consider negative numbers. There is no largest palindromic number - you can make them as large as you like.
1097