Welcome to TPT!
To grow "easy" plants you generally need between 1.5- 2 watts per gallon (wpg), so I'd say you need about 50-60 watts over your tank. There's no way 17 watts is going to cut it! Bulbs that are rated between 5000-10000k generally will support FW plant growth, so that part is OK.
I would take the plant out of the rockwool- that stuff is crazy messy and it's easier to remove sooner rather than later. Doing it in a bowl of water makes it a little easier.
With that kind of advice from your fish store guy, I'd also be suspicious of the plants that were sold to you - especially if they came from one of the big chain stores (which have been passing off all kinds of inappropriate plants as "aquatic plants" that don't have a shot at living under water!!)
Any way you can post pics of your plants so we can take a look? You might want to double-check on the plants before removing the rockwool, in case you want to take them back...