Although TRH has other regulatory mechanisms, the main mechanism is negative feedback, where thyroid hormones (T3 and T4) produced by the thyroid gland inhibit the release of TRH in the hypothalamus and thyroid-stimulating hormone (TSH) in the pituitary gland.

Yes, majority (if not all) of hypothalamic hormones have negative feedback mechanisms and are typically inhibited by increased concentration of both pituitary and respective target gland hormones.