To = preposition
Two = a number
Too = ??
Also, what is the correct abbreviation for “continued”?
(cont) (cont’) (cont.)
Too = adverb
and, according to The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
contd.
…without a full stop after it, because the last letter of the word is present.
“Cont’d” must have an apostrophe.
I thought so too, but I looked it up.
If you can find a definition with the apostrophe, please post it. That’s the way I was taught and now, having found “contd.”, my head’s beginning to hurt. 
Contd., as an abbreviation, does not take an apostrophe. Would you start a letter, “Dear M’r. Smith”?
Contractions take apostrophes; abbreviations do not. A contraction is a function of speech, while most abbreviations are not. One may write contd, but would always say continued.
The adverb too means also or excessively.
Yes, ‘too’ is an adverb. (It answers ‘how?’)
Two is either an adjective (the two balls) or a noun (which two do you mean?).
‘To’ is a preposition (sock it to me) or and adverb (he passed out, but then came to).
Now, in researching this, I came across something interesting: the use of ‘to’ in an infinitive (to run) kept being listed as a preposition in many online dictionaries. But, a preposition takes a noun (or noun-like thing, e.g., a pronoun or substantive) as an object. Never was it said that a preposition takes a verb. When a word that is normally a preposition is used with a verb (as in, ‘he came to’ or ‘I looked up’), it gets reclassified by its new function in the sentence (as an adverb).
And so, shouldn’t the ‘to’ in infinitives be classified as an adverb, or something exotic like ‘verb tense identifier’? It ain’t a preposition.
Peace.
I do wish people would let this silly and outmoded idea drop. Whether or not the last letter is present has no bearing on whether or not you should use a full stop. Either always use them or never use them. My own preference is for never using them: they just look awkward. Besides, who’s to say whether the “e” in “Ave” is the final letter of the word, or the third letter? Same with “St” for “Street”.