You know, it's funny that this topic has come up again because I just started reading "Studies in the Greek Church" by Archbishop Anthony Bashir and I came across the following information about candles and incense and I was thinking how useful someone may find it and then I come online and here is a topic all about it!
Anyways, on to the info!
ILLUMINATION: LAMPADS, CANDELABRA AND CANDLESTICKS:
In all churches, on the altar and on the Table of Oblations, also behind the altar and in front of the ikons, lights are kept burning, not only during evening and night services, but during the day services as well. They signify that the Lord gives us the light of truth, and that our souls burn with the love of God and are penetrated with feelings of joy and devotion. It is quite in accordance with this conception, that during solemn hoiday services and decreased during penitential services.
For the illumination of a church, two things are needed -- oil and wax. Oil (yielded by the fruit of the olive tree), is symbolic of grace, indicating that the Lord sheds His grace on men, while men on their side are ready to offer Him in sacrifice deeds of mercy. The pure wax, collected by the bees from fragrant flowers, is used as a token that the prayers of men offered from a pure heart are acceptable to God.
Of the candlesticks and candelabra used in the church, some are portable and some stationary, all varying in the number of candles or lamps which they bear. The candlesticks are always portable and carry one, two or three candles. One candle reminds us that there is but one God, Who is the Light Eternal; the candlestick with two candles is call Dykirion ("two candles"), and indicates that in Jesus Christ are united two natures---the divine and the human ; that of three candles is called Trikirion ("three candles"), and alludes to the three persons of the Deity. There are stationary candelabra, standing and suspended, in front of the ikon, bearing both lamps and wax candles. These are called candils or lampads if they carry only one candle; polycandils ("many lights"), if they carry seven or twelve candles (seven candles in allusion to the seven gifts of the Holy Ghost, and twelve in allusion to the Apostles); lastly panicandils ("all light") are those that carry more than twelve candles. Some times, in a panicandil is made in the shape of a circle, garnished with candles, it is called khoros, which means "a circle," "an assembly".
Besides the lampads, candlestick and candalabra, with their burning candles and lamps, an important item of divine service is the burning and swinging of incense (a fragrant tree-gum). This swinging is performed sometimes before the altar and ikons; then it expresses the wish of the worshippers that their rayer may ascend to Heaven, as the fumes of incense mount aloft. Sometimes the incense in swung towards the worshippers; then it expresses the wish ofd the celebrant that the grace of the Holy Ghost may encompass these souls of the fiahtful as the frangrant cloud of the incense encompasses them. The vessels which holds the incense is called censer; it is a cup with a cover running on three slight chains, which all unite into one handle.
Hope that you find this info helpful!