1. you must send spy to other player province and after spy arrives, you can try to infiltrate it. chances depend on your spy lvl and other player border lvl. its explained nicely in manual.
http://www4.imperiaonline.org/forums/int/index.php?topic=25.0 Calculation of spy success is explained in link i gave you. if you wish to calculate success of battle, use battle calculator.
2. you are attacking with -20 morale because enemy surrounded his province with 4 provinces in shape of + . its called walled province. you can do it to. so then enemies will get - 20 morale when attacking you in that prov.
Boxing a province
If a province is colonized, along with four other, cross way, then the middle province is considered inner colony and causes 20 points drop in morale to the army of any invader who attacks that inner province.
prov 13 is walled.
