I will try and answer this:

The rambler tickets are the same price on Leap, the difference is that you don't have a rambler ticket, it is on the Leap card instead.  The leap offers far more opportunities than Oyster.  You can have your ramblers on Leap and still use it for single journeys, just tell the driver that you wish to use a rambler rather than the single fare.  or vice versa. 

I assume that the personalised leap is for certain tickets such as monthly bus and rail etc. ie the ones that you always required photo id for.

Capping:
Easiest way to explain this is that once you reach €6.90 in Dublin Bus fares in a day, you don't pay any more that day.  So you make four trips, it costs €7.00, you pay no more and the leap is credited with the 10c.  The capping does not include Airlink, the rambler does so be careful of that.  The same works for the weekly cap which at €27.50 is very good value at less than €4 a day.  And for €10 a day you get Dublin Bus, Luas and Irish Rail Commuter and DART for the day, really good value.  

An off-peak oyster was £8.90 and an all day ticket was over £15.  Even though the Dublin Network isn't as big!!!