I currently have 3 boys using this program, one in Level 1, one in Level 2 and one in Level 3. We've used it for 2 years now.
You only need one "student materials". They are a package of cards with the phonogram sounds, spelling words, rule cards, etc. You cut them out and put them in an index card box with dividers. Each lesson you'll review cards, use the "new words" and put cards in Mastered or Review. I sometimes have two boys working in the same book and I just use two different bookmarks to show which kid is where. And I only use the "word cards" for one of the boys. 10-yr-old son never misspells a word. Ever. And he's in Level 3. 7-yr-old also never misspells. 11-yr-old gets words wrong frequently so I use the green word cards for him. If he gets it wrong, the card goes in the Review section to be worked on each day until he spells it correctly. If he got it right it goes in Mastered. If you had two kids needing the cards you could figure out a system to keep track of who was where or who needed to repeat words. (The spelling words are listed in the Teacher's book...the cards are only to keep track of which words were misspelled. The teaching book explains the Rules, but does not have them written out each day for you to review....you could add a sticky note to remind you which kid is working on which rule.) I do use the "rule cards" for each boy - I just grab them out of the section and spend 10 seconds flipping through to see who has passed while Step and thus which "rules" they need to review. If it truly drives you crazy then buy an extra student material package...but you might want to try it without.
I started everyone in Level 1 two years ago (well, 7-yr-old didn't start until this year). I wanted them to have a solid background in the 'rules' she explains. We had no previous grammar or spelling experience, however. One boy flew through the book in about a month and still remembers everything. The other son took many, many months. Third son is now flying through. I'm glad we "backtracked" because some of the most basic rules are explained in Book 1.
The Basic package worked just fine for us. I found index boxes at the office supply store and I store everything on a shelf in the schoolroom so don't need a tote. I personally liked the tiles they came with because they had all the phonogram sounds and blends and such.
I think someone mentioned this earlier, but as you progress you begin dictation. At first it's just words, then short phrases (like the black bat) and then sentences. In Level 3 my son is currently doing 12 sentences per lesson. I have them do copywork separately because their handwriting is fairly boy-like and they need additional practice. Usually it's only 1 or 2 sentences a day though since they are writing in spelling and other subjects.
I haven't used Spelling Wisdom so can't really speak to that.