I have Peach, Plum and Apricot which are self fertile.

I don't believe Apricot is reliably self-fertile in the more northern zones and certainly many plums are not. J.H. Hale is one peach that needs cross-pollination.

Adams County Nursery used to call their cots self-fertile but years ago I noticed that they were much more consistent when I planted 2 varieties at a site, now Adams agrees. Once in a while the practitioner gets one right.

It varies. Some sweet cherries are self fertile (Stella/Lapins/etc), some plums may be self fertile? Most I know of require a pollinator. Apple needs a pollinator. Apricots in my opinion need a pollinator. Peaches are self fertile for the most part. Grapes I think are self fertile. Pears for the most part need pollinators.

One issue you could run into, if you plant one and get fruit, is that if there is another tree in your area, it may be helping with pollination. A good example would be apples. Almost every neighborhood has some sort of apple that could be used as a pollinator.

Thanks to all. I decided to be on the safe side I will pair my trees. I don't want to spend all this money and efforts and get nothing. I have Figs too but I many Varieties for cross pollination although I know Figs are self fertile but with cross pollination you get better tasting Figs.
Abe

don't just pair your apples or cherries as most require another variety to pollinate