Q: By leaving push setting on, does it constanty check thus consume more data then by choosing hourly or does it depend on the amount of emails that come in? for example if I get very few emails (2-3) it be better to leave push on rather then check hourly?

I would answer you this way for the question about using the 'push' email option.

Turn off the push and 'fetch' options setting fetch to manual.

After disabling and changing fectch to manual go ahead and send yourself an email at your email address listed in your phone and notice what happens when you receive the email.

The Push and fetch feature will continually (based on the fetch settings) communicate back and forth with your email server(s) as often as you have the fetch feature set to check regardless of how many emails you typically receive in a 24 hour period.

good luck.