yes, the hole should be 2 times larger than the root-ball.
bone meal is good. so is rose
food pellets when you first plant
the bush...sprinkle about a teaspoonful in the hole and then sprinkle a light layer of soil on top of it and then put the bush in and fill the hole with more soil...i usually put another teaspoonful near the top of the hole too if the tap root is really long.
cover with soil to just below where the graft is. and then water thoroughly...let it soak down for about 30 minutes and then do another soak. cover with mulch - being careful to leave a clear area directly around the base...a couple inches wide. (mulch should never actually touch the base of the plants
when doing further waterings, water at the 'drip line' so that the roots will reach out to get to the water. the 'drip line' is the area directly beneath the outer-most leaves. you need to water directly at the base, too, it's just that, if you focus only there, the root system will not get as well-established as it should...watering at the drip line forces the roots to spread...
what kind of soil do you have? well drained? clay-type? rocky?