1-2 weeks is fine. Really the only thing you are quarantining for is bugs, snails, and diseases, but diseases will go away in tap water. I personally never bother to quarantine, but I do if it obviously has signs of algae or snails. I try and stay away from those plants when buying in the first place.
The water lettuce is fuzzy and is rather dull in color. I gave you a lot more of it than the frogbit.
Frogbit is the one that was in the same bag as the guppy grass. It is very vibrant in color and is smooth upon touch. These sol also grow some pretty impressive roots. I had roots that almost went to the bottom of my 15 gallon, which is about a foot high.
I would suggest quarantinimg any plant. I feed live foods a couple of times, so you don't want any kind of living thing with the plants besides the plants. Safer that way anyways.
Put the plants in regular tap, don't add dechlorinator, it will kill all the bacteria that isn't dead yet. Let them have sunlight and make sure they are all in the water, they get very fragile when there is not a whole lot of water so be careful with them. Some will probably be damaged as some ar pretty sang big.