Driving Lessons

[Sanhestar]

and some more on building duration

http://www.clickertraining.com/node/1056

if you check out that site you will find several other explanations about f.e. targeting, etc.

Targeting could also solve your problem of Koby rushing ahead on the way home. You would start with him walking next to you, keeping his nose/head at a certain position. Then shift the criteria to him keeping his shoulder at a certain position next to you. Then his hip, then his tail, then he has to keep the same distance in front of you.

As soon as you work with the cart, the target behaviour will be to stay between the shafts.

As always: start small, reinforce often, look for signs that you do not reinforce enough (I would hazard the guess that these are the times when he dashes towards food on the side :-) )