TOO DIFFICULT, TOO MANY QUESTIONS, TOO MUCH TIME

Demasiado + adjective/adverb = TOO + adjective/adverb:

The fur coat is too expensive.

Question number four is too difficult.

These shoes are too big.

She speaks too quickly.

Demasiado "a secas" = TOO MUCH:

Don Quijote read too much.

I love her too much. (A strange thing to say, but it's possible)

Demasiado + uncountable noun = TOO MUCH + u. noun

He eats too much fruit / cereal.
She drinks too much milk.

There was too much traffic.

He gave us too much homework.

Some politicians earn too much money.

Demasiado + countable noun = TOO MANY + c. noun
She invited too many people.
Do you think there are too many children in this class?
Don't eat too many sweets!

An exception: He gave away too many clothes, and now he's got none. "Clothes" is actually not countable, but it is a special word, because it is both uncountable and plural (something rather unusual). TOO MUCH is never used with plurals, so we say too many clothes.

Common mistakes:

There was too much people >>> There were too many people. ("People" is countable AND plural)

It was too much hot / small, etc. >>> It was too hot / small, etc.  (¡Ni TOO MUCH ni TOO MANY: no acompaña a ningún sustantivo!)

ALSO, TOO

Both ALSO and TOO mean "también".

TOO appears at the end of the sentence:
I'm tired. My children are tired, too. (My children too are tired)
She works from Monday to Wednesday. She sometimes works on Thursday, too. (Too, she works...)

ALSO is occasionally found at the beginning of the sentence, but it usually goes with the verb, in mid-position.
Do you remember the position of adverbs like always, hardly ever, etc.? Before the main verb, after the verb TO BE. Well, that's what we call mid-position, and it's the same rule for ALSO:

My sister sings in a choir; she also plays the violin. (Before the main verb)
He can play rugby and football. He can also take very good photographs. (Before the main verb)
She's young and beautiful --she's also very vain. (After TO BE)