Your concrete choice and rebar should be fine. I think the fiber glass may be over kill, normal steel rebar should work too, depending on price, but it's up to you.
The important thing with the rebar is it needs to be attached to the adjacent pieces of concrete to insure they don't shift relative to one another. Get a 1/2" masonry bit with a hammer drill, these can be rented for reasonable cost, drill holes 2-3" deep into the sides of the adjacent pieces of concrete every 12" or so, care should be taken when drilling not to drill too near the surface or to angle up to the surface as you can crack the existing slabs. Hammer the rebar (~12" length) into the holes, it should be a tight fit, but again be careful not to break the existing concrete.
Your 'rock' layer should be 3/4-"three quarter minus" gravel and can be ordered by the truckload from any gravel/concrete supply place. The minus means they keep the fines from breaking up the gravel which will make it compact tighter than washed rock would. 1" would be pretty low thickness, depending on the soil type, I would say shoot for 4" of rock. Important when excavating not to undermine the existing slabs. The gravel needs to be very well compacted. Hand compactors will work, but I would recommend renting a mechanical one. Spraying down with water will help compaction and keep down the dust.
Place 2x4 forms along the outside edge and put wood stakes about every foot or so on the outside of the form. Secure the 2x4 forms to the stakes with screws to keep it at the desired height, which in this case should just line up with the existing concrete. Make sure the screws are from the outside stake side into the forms and not the other way around, otherwise you can't unscrew them after the concrete is poured.
Your concrete choice looks fine, keep in mind if using bags you're going to need a lot of them. My rough estimate, assumed your slabs are about 6'x6' and 6'x5' so about 66 sq ft 4 inches deep makes 22 cubic feet (5 inches pushes it up to 27) or a about a cubic yard (27 cu ft = 1 cubic yard), when estimating concrete always round up it's much better to have a little too much, I would order 1.5 yards in a ready mix truck. For reference if ordering in a mix truck they carry around 9-10 yards of concrete and most places will have an additional short load charge for less than a certain amount. This may still be worth doing as those bags are only 0.6 cubic feet each, making it about 40-50 bags, which if hand mixing in a wheel barrow is a lot of work moving bags and takes a long time. You can also have issues as you can probably only mix 2 or 3 bags at a time, so you have to mix fast so the concrete doesn't dry out in the hole before all of it gets mixed and poured.
Speaking of drying out you want to wet the existing concrete and the gravel just before you pour or the dry concrete and gravel can suck the water from your mix and dry it out really fast at the edges. Also you want to pour when it's not going to rain, but really hot days are actually not great either as it will dry really fast making the finishing difficult and very unforgiving for someone unexperienced. If possible pour in the morning when it's cooler out. Don't put off cleaning your tools. Have a wheelbarrow or bucket full of water nearby for this, note: not where it will spill into the concrete.
You are going to want to put some joints into the new pads to line up with the existing pieces. something like this to control cracking:
For finishing you will need at minimum a trowel to smooth it out, an edger to round out the edge and a groover to make the middle joint lines. A string pulled tight and snapped onto the concrete works well for making sure you get straight joint lines.
You shouldn't need expansion joint filler for the small outside bits you're adding.
When you're done pouring make sure it is marked off or you stay nearby as it can be marked up or otherwise have impressions made into it for several hours, even when it seems completely dry. After pouring a friend's patio we went inside to relax after the hard work was done, while unknown to us his 5 year old did circles on the new slab in his tricycle, It seemed completely dry but those faint circle lines are forever.
After about 24 hours you can pull the forms out and backfill the edges with gravel/dirt/grass. You need to keep heavy loads (like cars) off of the concrete for about 2-3 weeks, it's still hardening even if it looks completely dry, I would recommend a cone, garbage can or sign of some kind; or you might get someone driving on it without knowing.
Hopefully this helps, it's a lot I know, I've done way too much concrete. Good luck.
