I absolutely would not tie the slab into the foundation. The loading on each and the support under them is different, and it is quite plausible that differential settlement will occur between the structure and the floor slab. I have been the expert called in on numerous settlement of structure/floor problems, and the ones where the floor and foundations are tied together, either through a ledge or through pinning are much more difficult and complex to correct. I have seen several projects where a differential settlement of a pinned floor/foundation caused cracking or spalling in the foundation, requiring a difficult/expensive repair of the foundation, where otherwise there would be an easy/less expensive replacement of only the floor slab, or would have been no damage to either if they weren't pinned together. Now, I specify a 30 weight asphalt felt strip be placed at the junction, to insure that they act independently.
I have seen several floor settlement cases, where they were not pinned to the wall. In those cases, there was no associated wall damage, and the repair was an easy (but of course expensive) slab replacement and subgrade remediation.
On the rebar/mesh/fiber issue, it is more or less a personal choice and what your chosen contractor wants/will do. I have no doubt after many years of professional engineering evaluation/design/inspection experience of concrete structures that reinforcement is a positive thing. It's like seat belts, everybody can cite an instance where someone got hurt or burned up or entrapped by a seatbelt; yet the hard, scientific evidence is that wearing a seatbelt is a good thing. There is really no doubt that reinfocement in concrete improves its strength and performance overall. Yes, it has to be installed correctly. Yes, you can find obscure/rare instances where it caused a problem. Overall, you're best off including it, as there is a positive benefit. However, it comes at an increased cost. The argument can be that it isn't worth the increased cost, because your application is so low performance that a failure due to no rebar isn't of any significance, or is improbable. Yes, good subgrade preparation and subsoil conditions make settling of a slab less probable. However, it's extremely difficult to accurately predict whether you have good subgrade and subsoil conditions. Proving that with any certainty costs way more than including rebar for homeowner type projects. In critical, expensive applications, evaluation of the subgrade and subsoil conditions is performed. But, rebar, carefully designed, is also included.
You pay your money and take your chances. Slightly easier placement of the slab, a bit lower cost, balanced against the slight risk of displacement at cracks. Neither way is absolutely right or wrong, it's just a balancing of risk versus cost.
