Ricotta salata is more like feta cheese in texture. It's not the same as ricotta cheeses

Would it be the same as Mexican Crumbling cheese? Queso fresco. Which has a feta like texture but only a slightly salty mild taste. It's very widely available here.

Ricotta salata is saltier than Queso fresco but it is a similar texture

Wikipedia explains the difference between ricotta and ricotta salata very nicely: In addition to its fresh, soft form, ricotta is also sold in three preparations which ensure a longer shelf life: salted, baked and smoked. The pressed, salted, dried, and aged variety of the cheese is known as ricotta salata, is milky-white and firm, and used for grating or shaving. Ricotta salata is sold in wheels, decorated by a delicate basket-weave pattern

In Italian "ricotta" means "recooked" and "salata" means "salted". It's a cheese made from yesterday's whey which is skimmed and strained into rush baskets (hence the pattern on the outside). Salted, it is "aged" for 15 to 30 days. Depending on the region it can be made from cow's, ewe's or goat's milk.

The two are not interchangeable though in terms of cooking/recipes, correct?

Mizithra is a fairly good substitute if you have trouble finding ricotta salata.

I think that Sam1148's suggestion to use queso fresco is a good one.