Should I have iMessage turned on or off?

I just got an iPhone 5c, I've never had a smartphone before. I just recently turned my iMessage ON as well as still keeping SMS ON. I'm a little confused and concerned. My boyfriend doesn't have an iPhone so will he still receive my texts since I have them both on? Is it better to have iMessage on or off? I have Sprint which I believe has unlimited data… Sorry I'm bad at this smartphone life lol.

Iphone 5 won't connect with car usb port?

I have a bmw 328i xdrive with a usb port and i plug my iphone 5 into the charger and it works for a few seconds then says something about being unsupported and then runs off battery again is there anything i can do to fix this

Free Iphone apps like Fitbit?

To use Fitbit, I think you need to buy Fitbit Flex.
Do you know of any free ios app that tracks your steps, squats, sit ups etc?

How to appear offline on facebook on iphone?

I know how to make myself invisible and "turn off chat". I just don't want anybody to see a green icon next to my name ever. Someone I know did it but I'm not sure how. Someone help me out please!

Is this enough space to record this video on my iPhone 4S?

I have an iPhone 4S and as of right now it has about 4.3 GB left. My mom wants to record something I'm a part of and it will last at most 15 minutes (put into 3 separate segments of video). Will I have enough space to record all of this program? (Note: iPhone 4S records at 1080p and I believe 30fps)