Of course it's legal! It's however not legal to sell the harvested leaves without a special license. Growing for home personal use, or as a decorative plant is totally legal.
Time of year depends on what state you are in. For northern states such as my home state of Michigan it's best to start them inside around March to April, then transplant them outside after the danger of frost. They do well in most soils, but if you have clay it should be broken up a lot, with peat moss added. They will also grow to about 5 to 8 foot tall, with huge broad leaves, so they can take up a lot of space. As for instructions, sorry I will not be including any, but I encourage everyone to Google any, and all of my seed/plant auctions for instruction, and or info.
I had already answered the question concerning instructions, but since you are not the only one who asked, I guess I could include them. :) As for it growing in NJ, yes they should be able to do well.