Yes 6500 is fine.
Adding more CO2 will help any plantd tank. HC is especially picky and I would say it is almost a necessity.
You can also get a 27w 6500k CF desk lamp at Home Depot. Its around 20 dollars and I have only heard good things about that lamp. Remember that adding more light without increasing the available nutrients, ie ferts, for the plants will only give you an algae farm. Also without the right amount of CO2 or ecel you will also be limiting the plants and algae will be more than happy to make up te difference.