I'll try to hit the highlights w/o writing a novel:

I have a 7yo Highland home w/ a 10 year foundation warranty. I had cracked tile, spreading expansion joints, cracked brick mortar across the front of my house. There are effectively 0 of any of these issues on the back 3/4 of the house. I contacted the home builder and they sent out a post-tensioning engineer company who said "at this time it's not out of range" (I think the report said I need a 1"1/4 elevation difference over a 10' span - which seems huge). The report also suggested that the cracked brick over my garage door was probably due to the lintel movement and not part of the foundation movement.

A little over a month later:

I now have drywall cracks across ceiling and starting down the wall. The gaps in the tiles are much more visible. New cracking mortar around bricks and stones out front. One of my interior doors in this area no longer latches and it jams when it's forced closed. I measured the drop with a laser level and see that it's near 1".

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Do I just have to continue letting my house degrade in order to qualify for the 1"1/4 slope difference?

Should I contact a property/construction lawyer to ensure that items such as the bricks over the garage door be included in the foundation repair?

Have any of you ever had a repair like this performed in or out of warranty, and what was your experience like?

Is this something that I will have to divulge in the future upon selling the home, and thus is it possible that this has hurt my home's value?

It sounds like this was a recent development or recently got worse by your post. If either are the case and you are in a drought like the rest of us it may very well just be soil moisture. Are any visible cracks at the foundation exposure V or ^ shaped, ie wider at the top or bottom? Couple of easy things to do now:

• At a minimum get a soaker hose around the foundation, especially on the side that is dropping.
• If you have plumbing supply in the foundation, especially if it's copper, do a pressure check to make sure you don't have a slab leak. Perform a static test on the drain system for the same reasons.

Highland is one of the better builders imo, at least in SA, but these conditions are hard on foundations if you have expansive soils at all.

The process will be long but do what SteveBott said above. The builder will delay doing anything for as long as possible. Navigate this with an intelligent real estate attorney while trying working through all warranty remedies available to you. Yes, you have to disclose everything upon selling. Don't waste any time considering hiding any known faults.
My father went through this in another state with another builder. The builder finally did a round of repairs. The underlying problem wasn't fixed so the problem reoccurred after warranty expired. Without an attorney, he had to pay everything out of pocket (not sure if he tried to file insurance claim).