Can I use iMessage on my ipad but also send texts using my Android?

Phil answered your question but I also want to add that you will not be able to iMessage with somebody unless they are already set up to use the Messages app on their devices. So if you try to text another iPad only user and you get the red circle, that means that they have not registered and set up messages on their own device.

The short version is that Message is an app - and it has to be turned on with a registered email address or iPhone number before it can be used.

Depends on how they want to contact you.

If they wish to send a message you receive n your iPad they will have to be using an Apple device nd send a message using whatever email address you have set up under Settings->Messages->Send & Receive->You Can be Reached by iMessage At:

Whatever you have there, is what the need to have in the contacts to send you an iMessage to your iPad.

The iPad cannot use your Android phone number at all so it will not in any way be associated with the device or your Apple ID. You will be using your Apple ID email address as your connect address to use Messages. If you want to look at it this way, your iPad/iMessages will be associated with your Apple account/Apple ID, not with the Android phone number.

Where some users get into problems is if they go from an iPhone number to an Android phone number. That is not what you are doing.

An Android phone would not impact this since only an iPhone number can be associated with an iPad and you will not be able to send SMS messages from your iPad anyway. You will only be able to send iMessages to other iOS users from the iPad. That will not impact the Android phone and the phone can't impact the iPad since it is not an iPhone.

You should get your answer by reading this:

http://www.apple.com/ios/messages/

Neither. Your android phone's number will not be associated with anything. Not your iPad nor your Apple ID in any way.