2)The employer should know the workload that is place on employees so they should be able to gauge if this is a reasonable statement. My husband (for eg) is not able to reply in a timely fashion to the hundreds of e-mails that he receives daily at work, & do his job as well as he does! However a good employee should be able to prioritise!
4) Disagree, training is needed in order to use e-mail facilities to best potential (not in all cases but in some). It shouldn't be presumed that people are comfortable with this media.