I understand your concern, as a former Protestant, I'll do my best to be concice.
First of all, the official teaching of the Church concerning worship is as follows.
2112 The first commandment condemns polytheism. It requires
man neither to believe in, nor to venerate, other divinities than the
one true God. Scripture constantly recalls this rejection of "idols,
[of] silver and gold, the work of men's hands. They have mouths, but
do not speak; eyes, but do not see." These empty idols make their
worshippers empty: "Those who make them are like them; so are all who
trust in them."42 God, however, is the "living God"43 who gives life
and intervenes in history.
2113 Idolatry not only refers to false pagan worship. It remains a
constant temptation to faith. Idolatry consists in divinizing what is
not God. Man commits idolatry whenever he honors and reveres a
creature in place of God, whether this be gods or demons (for example,
satanism), power, pleasure, race, ancestors, the state, money, etc.
Jesus says, "You cannot serve God and mammon."44 Many martyrs died for
not adoring "the Beast"45 refusing even to simulate such worship.
Idolatry rejects the unique Lordship of God; it is therefore
incompatible with communion with God.46
2114 Human life finds its unity in the adoration of the one God. The
commandment to worship the Lord alone integrates man and saves him
from an endless disintegration. Idolatry is a perversion of man's
innate religious sense. An idolater is someone who "transfers his
indestructible notion of God to anything other than God."47
-Cathechism of the Catholic Church
However, as you said, Catholics still do pray to saints and use art(including statues) in their religious life. This is not worship because in Catholic theology it is understood that saints are glorified persons in Heaven always ready to help us in our Christian life.
Let me give you a comparaison.
For example, a Protestant when in need of prayer he will ask his Christians friends to pray for him or even to personally help him out. Because he recognizes that adding their prayers to his does make a difference, and that asking them for help personally is completely warrented.
The problem though arises because Protestants, among others, do not understand that the imperfect Christians on Earth are not seperated from communicating with the perfect Christians in Heaven.
Hebrews 12:18-24 King James Version (KJV)
[Old Covenant, hesitation]
For ye are not come unto the mount that might be touched, and that
burned with fire, nor unto blackness, and darkness, and tempest,
And the sound of a trumpet, and the voice of words; which voice
they that heard intreated that the word should not be spoken to them
(For they could not endure that which was commanded, And if so much
as a beast touch the mountain, it shall be stoned, or thrust through
with a dart:
And so terrible was the sight, that Moses said, I exceedingly fear
[New Covenant, boldness]
But ye are come unto mount Sion, and unto the city of the living
God, the heavenly Jerusalem, and to an innumerable company of angels,
To the general assembly and church of the firstborn, which are
written in heaven, and to God the Judge of all, and to the spirits of
just men made perfect, 24 And to Jesus the mediator of the new
covenant, and to the blood of sprinkling, that speaketh better things
than that of Abel.
Emphasis added : Saints in Heaven are spirits of just men made perfect.
We Catholics understand this to be the consequence of being in Christ, of being part of his Mystical Body. That Body being what mediates when we ask the saints. As St. Paul the Apostle explains...
Colossians 1:24 King James Version (KJV)
Who now rejoice in my sufferings for you, and fill up that which is behind of the afflictions of Christ in my flesh for his body's sake, which is the church:
Thus far we have seen that it is logical for us to ask(the same as to pray) the saints in Heaven for intercession.
Now what exactly warrents us to use stautes, and to bow down to them, to be devouted to some of them?
It is right to warn people against the sin of idolatry when they are committing it. But calling Catholics idolaters because they have images of Christ and the saints is based on misunderstanding or ignorance of what the Bible says about the purpose and uses (both good and bad) of statues.
*One must understand that art aides us in triggering our human sensibility, like when you for instance keep pictures of people you like as for example your mother or even when you keep something symbolical concerning them. You would even be warrented to kiss the image of your mother or pay special attention to a royalty without being guilty of idolatry. Because to be in the sin of idolatry you need to make that person or thing your ultimate standard, your highest master... This distinction is indeed observed in the Bible.
To appeal to the 10 commandments about not making graven images is likewise a misunderstanding of the text as I will demonstrate(go to Catholic Answers for further details).
David gave Solomon the plan "for the altar of incense made of refined gold, and its weight; also his plan for the golden chariot of the cherubim that spread their wings and covered the ark of the covenant of the Lord. All this he made clear by the writing of the hand of the Lord concerning it all, all the work to be done according to the plan" (1 Chr. 28:18–19). David’s plan for the temple, which the biblical author tells us was "by the writing of the hand of the Lord concerning it all," included statues of angels.
Similarly Ezekiel 41:17–18 describes graven (carved) images in the idealized temple he was shown in a vision, for he writes, "On the walls round about in the inner room and [on] the nave were carved likenesses of cherubim."
If bowing to another human is idolatry, then why did Isaac allow Jacob to say: “May nations serve you and peoples BOW DOWN to you?” (Genesis 27:29)
If bowing is idolatry, then why did King David allow Bathsheba to “bow low and kneel before the king?” (‘What is it you want?’ the king asked. - No rebuke from David, 1 Kings 1:16)
If bowing is idolatry, then why did David bow down to Saul and “prostrate himself with his face to the ground?” (1 Samuel 24:8)
If bowing is idolatry, then why did Abigal “bow down before David with her face to the ground? Why did she “fall at the feet” of David? (1 Samuel 25:23)
I conclude by quoting St. Luke, when Jesus prayed and was transfigured.
Because in that moment there was a supernatural intercession of saints.
Luke 9:28-31 King James Version (KJV)
And it came to pass about an
eight days[8 is the number of new beginnings] after these sayings, he took Peter and John and James, and
went up into a mountain[hint] to pray. And as he prayed, the fashion of his
countenance was altered, and his raiment was white and glistering.
And, behold, there talked with him two men, which were Moses and
Elias: Who appeared in glory, and spake of his decease which he should
accomplish at Jerusalem.