Can i use one Apple ids for 3 Apple products for using iMessage ?

Yes.

 

Add your email into all three. The phone number and the email will be on the iPhone and just the email will be on the other two devices.

 

Add the email to both iPhones. If each each iPhone has phone service, they will have a phone number for iMessages and the email. If one iPhone doesn't have phone service, it will just have the email. The iPad will just have the email.

 

You should only have one email in there. When someone sends an iMessage to that email it will go to all of your devices. If they send it to a phone number, it will only go to the iPhone with that phone number.

 

Use the iCloud email on all three of them.

 

iMessages use cellular when WiFi is not available. You'll have to turn iMessages off when you are not on WiFi if you don't want to use any data on messaging. Texts use a fairly negligible amount of data. Pictures use a small amount, but videos use quite a bit and it can add up if you send/receive a lot of them.

 

WiFi is internet at home or provided by businessses. Cellular data is the data plan on your phone that you use when you don't have access to WiFi.

We? I don't recommend that to everyone. You said you were worried about using data.

 

Yes, iMessages uses data rather than cellular. Regular texting uses cellular.

 

If you text yourself, it is expected that you will receive the message on the same device it was sent from as well as other devices that have the same email account for iMessages.

Your wife should not have your email account listed in her iMessages settings.

Her account should have her phone number. An email account is optional. It should only be one account and it should not be your account. If you share an account she needs to set up a new email for iMessages so she doesn't get your messages.

You shound not have two phone numbers listed. You should have only have one email.