I've got 3 AFD frogs in a 10g with a few fish. I'm using an internal Whisper filter on the lowest flow. I've not had any of them get into the filter but I do have a piece of foil over the spot above it on the hood to prevent escapes.

As to the cleaning, you can use bleach,1 part bleach/10 parts water and let it soak with the plants for about 15-20 minutes. Then rinse, rinse and rinse again. Put in some fish dechlorinator and rinse a few more times. Let it airdry and check for any lingering bleach odor. Use a clean scrubby to get off any crud. NO soap.

Yes, use the light. No, don't use the gravel.