Yes, the purple is just a color variation, however, sometimes they will have color loss due to limited light we normally use in the soil based system-but it should still grow fine.
As for the plants-how many of the stem plants do you have-it is important to have lots of stems-The stem plants grow fast generally and are what help to keep the water safe until everything gets established.
What will your stocking be?
Filters-I don't have favorite filters-IMO/E they all do about the same thing-with that said, you want to limit surface agitation or too much since that can drive off the CO2. But, canisters with sprayer bars work pretty good since you can keep the sprayer bar under the water level. HOB's are okay-but if you plan on shrimp you have to be careful due to them being sucked up and the sponge filter is a good choice since you can have control of the flow if you use a gang valve. Or no filter at all and allow the plants to do that job. I don't always use filters-especially in my 10gal and under tanks-even on start up in a moderately stocked tank.