As we reach the altar, the altar is greeted by a kiss. In an ideal situation (which I have not) this can be done from the front side of the altar, so as to begin planting seeds for ad orientem worship. As Mass begins, there is an incensation of the altar. Incense serves many purposes: it smells nice, and it looks good. Beyond those two superficial reasons, there is the respect that is shown for the altar by incensing it.
Incense is also an apatropaic substance. meaning it repels demons! Demons are allergic to incense! So many people claim allergies to incense, and one has to wonder how much is in their heads. This is especially true when they start hacking up a lung before the thurible has even begun to smoke! Seriously though, it seems good to use something in divine worship that drives away evil spirits, because it is they who are the cause of many (not all) of our distractions in prayer.
Again, incense is a source of continuity of worship with the Jews. The same people who are gritting their teeth because they aren't allowed to say the ineffible Name anymore (because they think saying it relates them to the Jews, whom they are actually gravely offending), are the ones who don't like incense.
Once the Priest has incensed the altar (if he's allowed to do so), he retires to the presider's chair. This is a break with previous practice for presbyters -- only Bishops read the Introit and beginning of Mass at the Throne. It is good, however, to have the chair facing North (liturgical), toward the Ambo. The celebrant should turn to greet the people, then turn back. Again, this stresses continuity in some ways. It also underscores that the celebrant is not just presiding over a community, as though it were a board meeeting. He is leading them in prayer. At this point in the Mass, it makes sense that he should at least have the Tabernacle in sight. It certainly does not make sense to be looking at the congregation when not addressing them.
Now, the Priest is bound to hear some complaints about this. "You should look at us more!" These complaints stem from an insecurity that requires their egos to be stroaked by the Priest constantly gazing at them, even when addressing the Father!
This, of course, is one of the biggest problems with proper orientation of the altar to begin with. That horrible polemical term with his back to the people has been used to poison the minds of the People of God for half a century or more. As one Priest friend pointed out, no one complains that the bus driver sits with his back to the people. No one complains that a military leader has his back to the people as he leads a charge. Yet, when the Priest who is leading us on our pilgrimage to Heaven stands at the fore of the Body of Christ, they decide he has turned his back on them. Ridiculous!
To me, it is the height of arrogance for people to want the Priest to go into God's house and stand with his back to God, who, while omnipresent, is most substantially present in the Eucharist. Where the Son is, there are also the Father and the Holy Spirit. It never occurs to people that it's rude to walk into someone's house and stand with your back to Him! A restoration if orientation in the Liturgy will go a long way toward applying a hermeneutic of continuity.
With my current situation, I am in a parish with the presider's chair on the south side, but placed diagonally (which is it's own problem -- more on that later), so that the Pastor can sit facing the congregation, at least partially. I am forced, then, to turn in the chair if I wish to face the Ambo from which the Word of God is being proclaimed. There just seems to be a problematic understanding of where one's attention should be. Oh, and the eyes cast downward custom applies here as well. Certainly there is no reason to watch the congregation (which always mutiplies during the readings). The Priest, like everyone else, is supposed to be listening actively to the Word of God being proclaimed -- not paying attention to everything else that's going on in the church.