"Great Concentration and Insight says: 'If one lacks faith [in the Lotus Sutra], one will object that it pertains to the lofty realm of the sages, something far beyond the capacity of one’s own wisdom to comprehend. If one lacks wisdom, one will become puffed up with arrogance and will claim to be the equal of the Buddha.'”
I am Rev. Ryuei McCormick (Ryuei is my Dharma name, Michael is my secular given name). I also have had a lot of experience with Soto Zen and with Korean Buddhism in addition to being a Nichiren Shu minister (since 2001). So I'd like to offer some advice.
First of all - the Lotus Sutra assumes you know a LOT. It is very hard to read unless you already know the basics of Buddhism and Mahayana Buddhism. Having a study guide (a kind of Cliff's Notes) helps. I would recommend "Introduction to the Lotus Sutra" by Shinjo Suguro. As for the Lotus Sutra itself, before long the Nichiren Shu will be publishing a new edition of the translation by Senchu Murano, which is the one we use for our study and liturgies. However, I would also recommend the Lotus Sutra translation by Gene Reeves as being very accessible and also including translations of the opening and closing sutras of the so-called Threefold Lotus Sutra.
You can get the Intro book here from the Nichiren Buddhist International Center:
As for Nichiren's writings the Nichiren Shu is publishing a seven volume set in English of his writings. Six of those have already come out. They are also available through the Nichiren Buddhistm International Center bookstore.
But even more than the Lotus Sutra, Nichiren's writings are difficult to understand without a LOT of background and context - esp. in T'ien-t'ai Buddhist terminology and the context of 13th century Japanese Buddhist politics and sectarianism. To help with that I have been writing commentaries on my blog on Nichiren's major writings. The links to them can be found on this page:
Oh and on that page you can also find a link to Dharma Flower, my online book about Nichiren Buddhist teachings. You might even want to read that first.
Now as far as practice goes I also have a page with articles about practice:
Those articles should help you learn what you need to learn about how to actually practice Nichiren Buddhism. I think you might find Shodaigyo Meditation (article 7 on the practice page) to be particularly suitable for you as it is both minimalist, good for kids in that regard, and incorporates silent sitting practice.
Please read those through and feel free to ask any questions here about any particulars.
Namu Myoho Renge Kyo,