I've recently moved my fish from my 10g tank to a 75g tank and I really want to try out a planted tank in the 10g. It still has the cycled water in it and the filter is still running on it. I plan on pulling out all of the gravel out and starting fresh from there but I would like to know if it would be better/easier for me to just drain the water from the tank first or leave it in while I plant the whole tank (I'm trying to avoid having to cycle the tank again in the end).
Also, the tank is 20 1/4"L x 10 1/2"W x 12 9/16"H, I'm assuming that the standard lights in the hood/light combo it came with are insufficient. What type of lighting should I look for, for this size tank?
And finally, I'm looking at using a Marineland Penguin 150 filter(Filters 150 gal/hr), it's rated for up to 30g. I'm assuming that will be sufficient but, is it overkill to having that filter for such a small tank? I'm not sure how much more filtration is necessary for a planted tank, if any.

Thanks!
Brian