Apple tree in pot care

Hi all,

Picked up a mini Apple tree (will only grow to 2m tall max), re-planted into a 55 litre pot in some John Innes #3. Tree is suitable for a pot.

The info leaflet with it suggests thorough watering during dry weather in year 1, reducing the number of fruit to about 6 in year 1, and also feeding in march-ish time with some slow release fertilizer.

I really don't want this to die, so:

1. How often should I water in weather like what we have had this weekend? Every couple of days?
2. When should I be reducing the fruit on the tree? Obviously at the moment the tree is still totally bare, so now is not the time.
3. Is this slow release fertilizer in addition to the John Innes #3 it's planted in? If so, any suggestions on what to use?

Thanks all!