You can send and receive Text messages without a plan, you just pay per message. (I think it's $0.20 or $0.25 per message).
If you text a lot, then you may want to get on a text plan that gives you a bucket of messages for free. (i.e. $5 for 250 messages)
Tapatalk is a application on android that makes it easy to read and participate in online discussion forums. Not all forums support tapatalk yet.