As for the processor, it’s expected to ship with the A9X chip which is launching a bit later during the year. If that’s true, then it could also give some hints about the exact release date of the iPad Pro, or at least preclude it from coming out before a certain point.
Could the new iPad Pro feature USB ports? That doesn’t sound unlikely at this point, and there are rumors that claim it’s happening. However, it’s not clear if those ports will be replacing the Lightning connector, or if they will be additional options. Apple are very fond of their special proprietary connector and will likely want to stick to it, but on the other hand they will have to move away from the design at some point.
At least if they want to sell in the EU, as it will eventually be required to release devices with a standardized solution for their charging and possibly even data transfer, which would cause some problems for Apple and their Lightning connector.