The "word" that is manifested through preaching, is λόγος (logos):
The λόγος (logos) calls to mind John 1, particularly verses 1-3:
John 1:1-3 (ESV)
1 In the beginning was the Word, and the Word was with God, and the Word was God. 2 He was in the beginning with God. 3 All things were made through him, and without him was not any thing made that was made.
From these few verses, we see that the λόγος (logos), which eventually "became flesh" (see v. 14), is the means whereby God created all things.
In preaching, when the λόγος (logos) is manifested, what is happening is that God is using the λόγος (logos) to create. The audience, upon hearing and receiving the message being preached, has something created inside of them: faith.
When someone preaches the Gospel, and hearts are open (or opened) to receive It, God makes use of the λόγος (logos) to engender the necessary faith that saves. You get what you preach.
Even if you preach false doctrine, you end up creating false brethren. If you preach "another Jesus" the people who are open to that receive "another spirit" (2 Corinthians 11:4).
As far as Paul referring to a preacher being filled with the Spirit, i.e. to be "full of God's power", the answer is "yes", because (and this helps answer your question about the Book of Acts) we see several times that the writer of Acts explicitly indicates the following: being filled with the Spirit (Acts 4:8, 4:31, 7:55-56, and 13:9).
As these instances show, the men who were so endowed by the Spirit then began to preach.
Of special note is Acts 13:9-12 (ESV)
9 But Saul, who was also called Paul, filled with the Holy Spirit, looked intently at him 10 and said, “You son of the devil, you enemy of all righteousness, full of all deceit and villainy, will you not stop making crooked the straight paths of the Lord? 11 And now, behold, the hand of the Lord is upon you, and you will be blind and unable to see the sun for a time.” Immediately mist and darkness fell upon him, and he went about seeking people to lead him by the hand. 12 Then the proconsul believed, when he saw what had occurred, for he was astonished at the teaching of the Lord.
Note the sequence:
- Paul is "filled with the Holy Spirit"
- Paul denounces Elymas by the Holy Spirit with a gift of prophecy
- The very thing Paul prophesied against Elymas came to pass as the λόγος (logos) created Elymas' blindness
- The proconsul believed
This is the λόγος (logos) at work, being manifested through the Apostle. Acts really is the best, and I would say, correct place to see Titus 1:3 in action and fulfilled, at least in the lives of the earliest believers. Apart from Acts, you see the λόγος (logos) manifested in the life and ministry of the Lord Jesus, and the things He preached, in the Gospels.
Finally, why didn't Paul indicate to Titus that the λόγος (logos) is manifested through the written Scriptures?
Because the written words of the Bible are not what properly manifest or reveal the λόγος (logos). Only preaching the written words of the Bible does that. Hence:
2 Timothy 4:2 (ESV),
I charge you in the presence of God and of Christ Jesus, who is to judge the living and the dead, and by his appearing and his kingdom: 2 preach the λόγος (logos); be ready in season and out of season; reprove, rebuke, and exhort, with complete patience and teaching.
The λόγος (logos) is not just words, written or spoken. The λόγος (logos) is a Person: Jesus of Nazareth, the the manifestation of God in flesh.
To preach then, per Titus 1:3, is to do more than merely reveal what the Scriptures have to say about something. To preach the λόγος (logos) is to reveal Someone, to make Someone known.