Free Rules is a bit misleading. You get a few pages of basic mechanics, and a few pages of army construction rules. You still have to buy codices for each army you want to play/know the rules for. The army books have special rules, and data sheets for each unit with the special rules for units. You cannot play 40k currently without buying some form of rules.
You don't actually "need" need the army books, provided you have people playing Power rather than points. The new kits include the rules within the box. This isn't me trying to say "YOU CAN PLAY 40K FOR NOTHING!" mind you. But the price to get in isn't anywhere near as bad as it's been in the past, especially if you decide to start instead with Kill Team.
I'd be interested in Kill Team if there weren't already a much better skirmish style game on the market >.>
Kill Team isn't 40k. And the didn't lie directly when they said the rules will be free. But the withhold that there will be rules you have to buy to play 40k completely. It's not a way to get trustworthy
I feel like a lot of Infinity sits too close to home (by intent). Despite loving the faction, not sure I would walk around with a Haqqislam faction tattoo the same way I might have a Retribution of Scyrah one, for example. Crosses, standard text, basic logos that are taken from elsewhere (you can play spot the unit logo on a map of Japanese prefectural flags: http://www.earthlymission.com/wp-content/uploads/2017/10/japanese_prefecture_flag_map.png) ect... The Infinity world and much of it's iconography is setup to mirror much of what is already fairly mundane or too easily confused for something else in our world to make for all that interesting of a tattoo. Those new sculpts are pretty sweet though. They also fix the scale.