Once established both should grow a couple feet or more per year but most growth will bend down, with significant height increase not proceeding nearly as rapidly as with upright-growing kinds. You may see neither of them grow very much larger for a long time - this varies between different specimens. Neither are likely to shoot up much for years, perhaps eventually one or both will start sending up new branches that grow vertically for a bit before bending over, hoisting the canopy of the tree higher in leaps.

Do not plant either in an area that is at all damp or soggy, impeded drainage is murder on these. They also will be liable to have disease problems beset the tops in low places where the air is damp much of the time, even if planted on mounds or other spots where they escape the dampness of the ground.

Don't worry about any little cherries that may be coming along.

Great answer, Thank You Very Much!
Maggie

If you think any of the trunk sprouts may be from below the graft or will produce branches that are not desired for other reasons, such as distorting the shape of the tree from that which you want it to have (even though belonging to the weeping cherry and not the rootstock) then you certainly do want to snip these off.

Although some 'Snofozam' are grown from cuttings and other specimens of weeping cherries ('Snofozam' and others) are grafted near the ground and trained up on stakes to form a top many are still grafted on the tops of trunks of other kinds of cherry trees. You should examine both of yours and try to determine where they have been grafted (if both are, in fact grafted) so that you are able to identify rootstock sprouts and remove them while still small.

My gosh your both are grafted at the bottom. I don't know how I missed that.
I'm going to prune all the side shoots on the pink cherry and only the
very lowest shoots on the fountain. Thank You again!