Learn Hardcore Malay: Bas awam selalu penuh setiap pagi. - Public buses are always full every morning.

Bas is borrowed from English bus, and awam means public. In Malay most nouns do not change form for plural, so bas awam can mean either “the public bus” or “public buses” depending on context. To emphasise plurality you can:

Reduplicate: bas-bas awam
Add a numeral or quantifier: beberapa bas awam (several public buses), sepuluh bas awam (ten public buses)

Why is selalu placed between the subject and penuh? How do I know where to put adverbs in Malay?

Adverbs of frequency like selalu (“always”) normally follow the subject and come before the predicate (verb or adjective). The typical word order is:
Subject + Adverb + Predicate
So here:
Subject = bas awam
Adverb = selalu
Predicate = penuh

Why isn’t there a word like is before penuh? Aren’t we missing a verb?

Malay usually drops the copula to be. Adjectives can directly function as predicates without a linking verb. Thus bas awam penuh literally reads “public bus full,” which naturally means “the public bus is full.”

What exactly does selalu mean and how is it different from sentiasa, sering, and kerap?

selalu = always / frequently (habitual repetition)
sentiasa = always / constantly (emphasises unchanging state)
sering = often (less than selalu)
kerap = often (synonym of sering)

Examples:

Bas awam selalu penuh setiap pagi. (Buses are always/frequently full every morning.)
Bas awam sentiasa penuh setiap pagi. (Buses are constantly full every morning.)

What does setiap mean and why do we say setiap pagi instead of pagi setiap?

Setiap is a determiner meaning every. It always precedes the noun it modifies, so you say setiap pagi (“every morning”). Reversing to pagi setiap is ungrammatical in Malay.

Why don’t we add a preposition like pada before setiap pagi? Can we say pada setiap pagi?

You can add pada for formality or emphasis—pada setiap pagi also means “every morning.” However, Malay commonly omits the time preposition when the expression is clear, so setiap pagi is more natural in everyday speech.

Penuh means full. Do we need to say “full of” something? Why isn’t there an object?

In this sentence penuh implies “full of passengers,” and the object is understood from context. If you want to be explicit, add dengan:
Bas awam selalu penuh dengan penumpang setiap pagi.

How do I express the public buses are never full every morning in Malay?

Replace selalu (“always”) with tidak pernah (“never”):
Bas awam tidak pernah penuh setiap pagi.
You could also say Bas awam jarang penuh setiap pagi (“public buses rarely full every morning”).

How do I ask Are public buses always full every morning? in Malay?

For a yes/no question use adakah at the start:
Adakah bas awam selalu penuh setiap pagi?
Or in casual speech, just raise your intonation:
Bas awam selalu penuh setiap pagi?

Is it redundant to have both selalu and setiap pagi in the same sentence? Don’t they both indicate repetition?

They serve different roles:

selalu describes how often something happens (frequency).
setiap pagi specifies when it happens (time frame).
Combined, they mean “buses are always full during that specific period every morning,” which is both precise and idiomatic.