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Marko, You can never be too cautious..... I've watched this thread and kept my nose out of it. I just wanted to comment on a couple of things.

Sdpasific: By skipping the acid/neutralize step, you are cheating yourself and the customer. If you look at a piece of concrete amplified many times, it looks like a honey comb of holes. By skipping that step, you are leaving behind years of contaminates in these tiny crevasses. You apply your base coat and the hybrid polymers "attempt" to do their job to penetrate these tiny holes and they leach out all the crap left by not etching them out. The stains are the bye products of short cutting the procedure. Now lets spray on another block by trying to cover up the leeching of a dirty floor.
The spider cracks can be caused by several factors:
1. The water in the mix has no where to go  because of the resist you have sprayed under it and the improper prep. It lays on top, keeping your TF wet. It finally dries and causes shrinkage cracks. If you force dry it that can cause it to shrink too fast and cause it also.  
2. There may be a chemical reaction to the "paint" product you applied under it. Maybe it didn't happen everywhere you sprayed your stuff on  because maybe these areas were sprayed heavier and/or not completely dry. I haven't a clue......
3. Partial bag mixes can sometimes do this.

Tile ghosting: A pain in the arse for sure but knowing why it happens can help in the resolve. Concrete takes years to cure. Concrete is also like a sponge as it allows moisture to migrate through it. Where you get into trouble with a non breathing sealer is when there's too much water migrating and builds up pressure. There's ALWAYS moisture migration in concrete.

Besides the dirt build up in these "access" areas of the tile grout/joint lines, they also are also the pathways for concrete to breath. This causes a chemical difference in the curing of the concrete. When ever there is a difference in the drying/curing of concrete, it will cause a color shift and/or reaction when applying anything on it. It will cause a difference of drying times, color absorption.

As ecHouston stated on polishing, the chemical makeup of the concrete along the tile lines makes it impossible to make the lines dissappear...... well, you can grind really, really deep but it will show more agg size and still may not get all the lines out. The epoxy with silica sand to rejection is a sure way. I've used a heavy loading of charcoal on my base coat and that masked the grout lines. The ultra stone sprayed between base coats works pretty well but you're playing with fire because if that dries before covering, you just created a bond breaker that will cause problems later.

The best way I have dealt with lines is to apply a more concentrated acid etch, neutralize and wash, wash. Use a heavy dose of pcc on base coat and then apply regular coat of TF. If they still ghost, bite the tongue and apply a third base coat. (This is when I think to myself that maybe the epoxy and sand would have been cheaper.... and quicker).

Etch and clean your floor and you will not get the "yellowing". I strongly suggest not using  the kilz, binz or whatever on the nicely opened slab before applying or reapplying your base coats. If you can take a 6" razor scraper and scrape off your base coat....... do so. You only have a mechanical bond and it may fail later. Anytime I have a stained area on the base coat, I scratch the heck out of it to make sure it has a chemical bond. I get stains sometimes along a control joint that has leached up excess moisture.     gene  ec-Indy