The Caravel Harness consists of a clocking module. What is the maximum frequency that can be passed as a user clock through this clocking module into the user space. Also, are there high speed IO pins and what is the maximum speed they support?

The user clock was tuned to a maximum rate of 214 MHz but it doesn't go that fast due to unsimulated parasitics. I measured the value but I don't remember what document I put it in. The GPIO pads have a maximum speed of 60MHz. If you want a true high speed I/O pad, you can use one of the analog pads from the caravan design, but you will have to implement some kind of ESD protection yourself, because they don't have any.