Although you specify the FR-V200 and others as the inverter models, CC-Link is currently supported by the FR-A500 and FR-E500.
The FR-V200E does not support CC-Link.

1. Yes.
Information on inverter status (for example, faulty, operating status) can be sent via communication in any operation mode.
Also, by setting operation command source (Pr.338) to "1" at the PC link operation mode, you can set the frequency via CC-Link and input the start command from the external terminal.

2. You can vary the speed commands continuously via CC-Link. 　
The response time is approximately "Sequence scan time + Link scan time × 3 + Inverter processing time of 20 to 30 ms".
For the link scan time, refer to Section 5.2 of the CC-Link System Master/Local Station User's Manual. (It depends on the number of inverters connected, baud rate, and other factors.)

The response time for 0 to 10 V input is approximately 100 ms (initial setting).
Therefore, varying the speed commands in 20 ms cycle as you requested may not be addressed.

3. The inverter frequency is set by the instruction code written in the EEPROM and RAM (HEE) and by the instruction code written in the RAM only (HED).
The EEPROM is mainly used to memorize the setting frequency and the RAM is used to store the frequency used for actual operation of the inverter.

Since the EEPROM has the life for data writing, frequency writing to the EEPROM may damage it. Therefore, if you are changing the setting frequency frequently, use the instruction code written in the RAM only (HED).