Too many questions, I'll answer a few though.
Quote:Does Islam mean "submission"?
Islam the word means submission/surrender. Specifically submitting and surrendering instead of to your own whims and desires, to the commands of your Creator. The sun and the moon for instance, are considered "Muslim" (Muslim is the active participle of Islam, this also answers another question) because they submit/surrender to the commands/laws of God (laws of motion/gravity etc.) Now for entities like the Sun and the Moon, they have no choice in their submission/surrender to God's will, as it's just their function, but human beings have free will (this answers another question further down the list, I guess), and therefore must choose to either submit/surrender or to rebel/disobey. This is in fact the essence of all religions, that God has stated what the correct/moral way of conduct is, and then people either choose to follow it (submit/surrender to it) or they choose to disobey and rebel against it.
Quote:Must you pray 5 times a day?
The five 'contact' prayers are required of a Muslim every day, yes. But that is not all prayer/worship entails. A Muslim also prays extra prayers when he feels like it, or when certain circumstances dictate, for instance, during times of drought, it's recomended to pray and beseech God for rain. Muslims have regularly done this during Australia's recent drought, although I doubt most Australians know about this, as it can barely be noticed through the barrage of negative reports about Muslims.
So the 5 daily prescribed prayers are a way of keeping in constant contact/remembrance of God. It helps to keep the soul regulated and constantly spiritual, as it is always on your mind, and makes you take regular time out of your day to devote to the worship of your Lord.
This is something present in the Judaeo-Christian tradition, although Christians have probably neglected it quite a lot, Jews do indeed perform daily contact prayers (3 times a day though).
Quote:In prayers do you always address God as "Lord of the worlds"?
This statement is used in every prayer, as it is one verse of the standard surah of the Qur'an that is read in each prostration of prayer. However it is not the only statement used to address God. Each prostration of prayer involves reading the opening chapter (surah) of the Qur'an, along with some other verses/chapters of the Qur'an of your own choosing.
Quote:Must you prostrate yourself?
Yes, of course. Islamic prayer has a very standard form, which involves prostrations and bowing. Likewise Jews and Christians once prostrated in prayer, but don't seem to much anymore, if at all. Do you prostrate in prayer? If you pray that is.
Prostration appears quite a few times in the Bible, both in the OT & NT:
Gen 17:3 And Abram
fell on his face: and God talked with him, saying,
Num 20:6 And Moses and Aaron went from the presence of the assembly unto the door of the tabernacle of the congregation, and they
fell upon their faces: and the glory of the LORD appeared unto them
Jos 5:14 And he said, Nay; but [as] captain of the host of the LORD am I now come. And Joshua
fell on his face to the earth, and did worship, and said unto him, What saith my lord unto his servant?
Mat 26:39 And he went a little further, and
fell on his face, and prayed, saying, O my Father, if it be possible, let this cup pass from me: nevertheless not as I will, but as thou [wilt].
Anyone who's seen Muslims pray will know this is a description of how a Muslim prays, not a Jew or a Christian.
Tbey also used to make ablutions/purification before prayer same as the Muslims do:
Exd 40:31 And Moses and Aaron and his sons washed their hands and their feet thereat:
Act 21:26 Then Paul took the men, and the next day purifying himself with them entered into the temple, to signify the accomplishment of the days of purification, until that an offering should be offered for every one of them
Which as far as I know, Christians do not do before prayer, not sure about Jews.
Quote:Is that a sign of "slavery" to God?
It's a sign of willful submission and surrender to God. It's a sign we recognise his position as our Creator, and therefore we obey his commands/laws and reject being rebellious to him. If you want to call it slavery, great, but note that slavery has very different connotations in your language/culture than it does for Muslims and even in the Bible, where "servant of God" is a name used in your own Bible. In the Semitic languages, both the word for slave and worshipper derive from the same root, so there's sometimes some confusion for non-Semitic speakers to mix them up and claim ridiculous things like "Islam is about bondage". In the Bible itself, the relationship between maan and God is described with the same exact word as in the Qur'an, that of being a surrendered servant of God.
Quote:Is prayer more ritual, than a form of discourse?
As explained above, although there is ritually prescribed prayers, even they may contain 'free form' supplications. Also I think maybe you're confusing between prayer and supplication. Christians mostly just supplicate from what I know, they don't actually even have prayer per se. They perhaps just count their supplications as prayers. Whereas for Muslims we have both prayer and supplication.
Maybe I'll answer some more later, we'll see how we go..