
UK landline - the conventional house/office phones (like telekom). as opposed to the non-geographical numbers (starting with 0845 etc) and they cost a bomb to calls; in a region of 50p per minute. landline numbers are particularly useful if you want to use those international calling calls as they yield much more minutes, compared to dialing the toll free 0800 number instead
registered postcode - applicable to your desired postcode, for example CF23 represents the cathays area of cardiff, wales.
off-peak mins - self explanatory i suppose?
UK texts - cross network (applicable to other UK networks for example vodafone, 3, orange)
O2 mobiles - you cannot never tell from one's mobile number which network he/she is using, due to the number portability system (again self explanatory). your wife will have to ask the person in advance. hence my contact names usually go like this, BlackBerryBloke HP (Orange), Nokia2003 HP (Vodafone)
Unlimited texts to O2 mobiles - free texts to O2 lines (but it could be misleading as they usually have a quota/limit; standard industry practice)
call international landlines and mobiles from the UK - self explanatory.
i sure do hope the information above helps.