Here's the info about the PlayBook directly from RIM.
BlackBerry 4G LTE BlackBerry PlayBook Tablet PC - US
Note this page says the 4G LTE PlayBook which is available in limited markets. The original Playbook is wifi only. Look at all the tabs for features, specs, apps, etc. This should answer a lot of your questions about the PlayBook. Regarding the iPad vs. PlayBook it might depend on what you want to do with it. Using Bridge with your 9930 greatly enhances PlayBook -I it keep it connected 24/7 and always have internet access when there is no Wifi available.