CFI is all on your own. Get the CFI oral guide by ASA then hit the bold questions. Know the part 61 requirements for everything. There is no reason to buy any kit. I didn't even walk in with the FAR/AIM as it's not a FAA publication. Read the FAA books that cost roughly $7 or you can download them for free. If you read the FAA books then study the oral guide you are good to go. All you have to do is learn to land from the right seat and you are good there. Start studying before you start flying for it. It only takes a week to get the flying down but roughly a month of flying.
I don't believe you need any CFI with two years experience just one with 400hrs of instruction given. I could be off on that and don't feel like looking it up. Either way read part 61 and 91. Should take a month to get it all down solid then learn to fly from the right seat. Most guys are able to get it down in 15-20hrs easily. Then go to the FAA for the checkride and they don't charge. It's true they have a very high fail rate,80% in my area, but so long as you admit you're human and don't know something you'll be ok. Just don't pull answers out of your ass. Same goes for any interview.
Flying is one thing, instructing is another. Those that bash it are the ones who haven't done it. Usually you end up learning more from your students then they learn from you. It's hard to imagine with that commercial certificate in your hand that there is more to learn within the realm you currently operate but there is a TON out there. You'd be amazed at how many people with thousands of hours fail the PPL written if they take it again. A whole group of us did it online for fun right prior to leaving for the airlines and the results were quite funny. From a US Air Force Lt. Colonel to 6 others of us only 2 passed. A Martin Air pilot and myself
of course I went through it regularly with my students so I was up to date and shouldn't have been included in the group.