The older mare won in 2006, her daughter won in 2011 and will be off to Nationals again in a few days to face older horses this time. Your description probably could fit the halter ring though and I don't pay much attention to what goes on in that world...my mares both won their titles under saddle. I don't really blame people for not wanting to show especially with how expensive it is now (or for moving on to stuff like reining or racing where you can win actual money), but at the same time it's too bad because our shows could definitely use more numbers.
I haven't noticed a difference in behavior in foals that were weaned earlier vs later, but I would imagine it's more stressful for a younger foal. I have heard that their digestive systems aren't really meant to properly digest solid food until about 6 months.
I haven't really seen an emotional difference with Rowan- the QH I rescued when she was a foal. She has traumatically lost her Dam at only 3 weeks old, and was so neglected - 3 months later, she was near death. She had a body score of "1." She's 7 now and though never bred, is an affectionate, extremely social mare who loves humans. That may be the intense time we spent saving her, but it may be her nature as well. People may poo poo the idea, but I dare say this mare actually feels grateful for her life. I imagine her ability to be a good mother wouldn't be impaired in spite of her rocky beginnings.