Joge said: Some labs, however, make prints directly from mounted slides, but the results are not that good.
Nothing could be further from the truth. If the lab does it right, a print made directly from a slide (no inter-neg) will be way way better than anything you could achieve from printing a home-scanned slide burned onto a CD
But you could do it that way - home scanning, and it doesn't work out too bad with small size prints. Either way, for submitting pictures here, you really need a dedicated film scanner, not a flatbed. Once you've got that, you can as has been said scan print from a scanned slide, or for that really special job take the slide to a lab and get it printed properly.
In answer to what slide film... There's only one - Kodachrome 64!