Just to add my 2 cents...

If you are making an ooze and its type changes because of a template, it should change it. If it still has some remnants of its original type, then it should gain the Augmented subtype. Frankly, this strikes me that it should be an Outsider (Augmented Ooze).

Advancement: 7-12 (Medium) and 13-18 (Large). Creatures usually advance by one size category every time they double their HD.

Now that it has sentience, what languages does it speak? Infernal should be obvious but it should be able to speak 4 languages due to its Intelligence.