I'm sure others will have more to add but you seem to be onto the problem and the solution itself..
"My dad is a sucker for the cat, and anytime he does this to him he feeds into the behavior by walking him or feeding him. "
In my experience, and I'm actually going through something similar with my 2 year old, (lol) cats do best on a strict schedule of managed expectations.
This means being fed and walked at the same time each day. (Lucky that u can walk the cat, we may try as well).
If other family members/dad react every time they meaow, then they have trained you well.
It will never stop because everyone/every kitty loves free food and cheery walks (ok that's rare but the cat likes it so we are talking reward) as often as they can get them.
Also lots of human foods are bad for cats especially when we prepare them the human way.
All family members should be feeding/walking at the same or similar time imo.
AWESOME looking cat btw
Hope that helps.