No it would not effect the validity of the Mass but it is required to have a Crucifix on or near the altar when Mass is being celebrated. The Crucifix and statues are not supposed to be covered until after the Mass of the Last Supper.
Nothing. Behind the Altar, where the old High Altar used to stand, is the Cathedra, with a statue of St. Peter above it (St. Peter’s Cathedral Basilica). There are icons on the walls of the apse, but these are of the Apostles. The only Crucifixes are on the Side Altars, but they arent actualy in the Sanctuary.
Yes, mostly in older churches though. Many of the newer churches in my Diocese (c. late 60s to mid 70s) lack crucifixes. I have seen many bare crosses and one Risen Christ on the Cross, but with the exception of maybe two of the newer church buildings any crucifixes are limited to the older churches (except the Cathedral).
Like I said, it’s small and usually lies flat on the altar, so you might not see it, depending on your angle and proximity to the altar. I just know that it’s supposed to be there because I was told by very orthodox priest in Toronto that there’s always supposed to be a crucifx on the altar itself. I’ve also seen it there myself, since I often go to Mass in a fairly small setting at my university campus, so we get a closer view of the altar (and this particular crucifix is upright, so it’s easy to notice).
The Church in Canada is a real sad story. Liturgically, many Masses here would shock even Cardinal Mahony (one time I attended a Mass where the Host was square, dark brown and had the texture of a waffle). We are theologically backwards (our Bishops actualy voted to ignore Humanae Vitae and I have no doubt that Hans Kung would feel at home among most of the clergy here. Abuses are rampant. I know of several priests in my Diocese and others who are openly gay (as in concelebrating a “Mass” with Anglican ministers during gay pride week in my city) but have not been reprimanded. The same goes for several priests who have married (not previously married protestant ministers who have converted, but actual ordained priests who have married). The Catholic schools are a disgrace (the curriculum is watered-down and oversimplified, and many teachers will outright teach heresy- such as one year when we were taught that the Eucharist was “phyiscally bread and wine, but spiritualy the Body and Blood of Christ”, as well as the whole “God, He/She” thing).
If I didnt fully believe that the Catholic Church is the Church of Christ, founded on St. Peter, and that the Gates of Hell would never prevail against it, I would have run with open arms to the Eastern Orthodox long ago.