shall and will

[Saneta]

PLease tell me what is the difference between:
1. 'shall be able' and 'will be able'
2. 'shall have to' and 'will have to'

Is there any general difference between 'shall and 'will'? - Maybe this fact, that 'shall' we should ONLY? use for persons : 'I' and 'we' and 'will for every person/persons?

Thank You :-)

[Dozy]

This is such a frequently asked question, it might be best if you browse through http://www.google.co.uk/search?q=difference+between+will+and+shall and then ask any follow-up questions here.