Il lunedì bevo tè caldo.

In Italian, to express habitual actions on specific days, you use the definite article + singular day.
• Il lunedì = on Mondays or every Monday.
It’s just how Italian marks repetition: the article turns a single day into a recurring event.

Yes. Both mean every Monday:
• Ogni lunedì literally means each Monday.
• Il lunedì is idiomatic and equally common.
There’s no significant difference in meaning; ogni simply emphasises each occurrence more explicitly.

When talking about beverages or food in general with verbs like bere or mangiare, you typically omit the article:
• Bevo tè = I drink tea (in general).
If you include an article (e.g. un tè caldo), it makes it a specific item: a cup of hot tea.

That’s perfectly correct but slightly more specific:
• un tè caldo = a (single) cup of hot tea.
• tè caldo (no article) speaks of tea habitually or generically.

• tè uses a grave accent to distinguish tea from the pronoun te.
• lunedì (and other days ending in a stressed vowel) uses an accent on the final syllable to indicate stress.
Leaving them off is a spelling mistake and can cause confusion.

In Italian, days of the week are common nouns, so they’re written in lowercase (unless they start a sentence):
lunedì, martedì, mercoledì, etc.

Yes, tè caldo (noun + adjective) is the normal order in Italian:
• tè caldo = hot tea.
Putting the adjective first (caldo tè) would sound poetic or archaic, not conversational.

Tè is masculine, so with an article you’d say:
• il tè = the tea
• un tè = a tea
In bevo tè caldo the article is dropped because it’s a general statement about tea drinking.