Congrats on getting them all! It's not easy!
First question: There is no end. You can continue to catch all the bugs, or try to make the most money, or try to challenge yourself some other way.
Second: the only way to get that fence is through a mod.
http://www.ldwforums.com/ubbthreads/ubbthreads.php/ubb/showflat/Number/97502/page/1#Post97502
There is a whole bunch of them and I'm sure one of them had the other fence... I think... well if there isn't I can make one, but it'll take a couple of days.

Marcey