Tighten up those nuts and bolts on the side of the toilet to keep it from rocking. If you don't see the bolts, the bolts may have covers over them that you have to remove first.
If the toilet is continuously running, you need to replace the flush valve assembly, or part of it, in the tank. If the flushing sound itself bothers you, you might be able to buy styrofoam...
Shut the supply valve to the fixture and call a plumber to replace the defective parts flushometer diaphram, Piston assembly/ Float type flapper /disc , over flow tube and other related parts
When you're done, flush, Then wipe and flush again. Dont use as much toilet paper. Also hold the handle down so the water keeps running till all the stuff is gone. This turns your "low flow" into a...