OSPF Area 0 is a backbone area. Other Area must connect to Area 0. Virtual link use for connect to Area 0 pass from other area. When middle area is stub area we can use GRE tunnel.
Access-list is only the rule. You need to apply where you want to effect. Access list is a powerful tool but if you don't apply, it not more than a line.
EIGRP Neighbor Requiremnt- 1. AS 2. K value AS number must same number and K value too. Default K value is 1 0 1 0 0 you can see with "#sh ip protocols".