You are always going to get better image quality out of zooms that have a less aggressive zoom range. The 18-55IS and 55-250 are pretty good lenses at a pretty good price, but as mentioned you will have some trouble shooting indoor images of moving things. For that, you will really need an external (i.e. hotshoe) flash. Although the 50d has a built-in flash, the "look" you will get from that isn't much better than from a point-n-shoot camera. A hotshoe flash allows you to bounce the flash off of the ceiling (making the light look more natural since it is coming down), or at the very least add a diffuser (that softens the light). Probably the best choice of flash is the canon 430 or sigma dg500.
Current: 5DM3, 6D, 8mm fish, 24-105/4IS, 35/2IS, 70-200/2.8IS, 85/1.8, 100-400/IS v1, lensbaby composer with edge 80, 580's and AB800's
Formerly: 80D, 7D, 300D, 5D, 5DM2, 20D, 50D, 1DM2, 17-55IS, 24-70/2.8, 28-135IS, 40/2.8, 50/1.8, 50/1.4, 70-200/4IS, 70-300IS, 70-200/2.8, 100 macro, 400/5.6, tammy 17-50 and 28-75, sigma 50 macro & 100-300