Bebo is the singular, first-person conjugation, so it's used when it's the speaker that drinks. "Eu bebo água" = I drink water.
Bebe is the singular, third-person conjugation, so it's used when speaking of someone that drinks. "Ela bebe leite" = She drinks milk.
The "T" in portugues sounds allways as an english T (like Teacher like someone told you), but it sounds as "ch" only when itfollows an "e" or an "i", like in the words "notícia>/nochísia/", "forte>/fojchi/"...
MangoHero1, yes, it happen in almost all cases, but only in Brazilian Portuguese. In other country like Portugual, Angola, Mozambique, etc., The sound is the same with "tea, teacher, touch, tittle, tiger."