This could also be a result of something that is not the toilet at all. If the noise is coming from the drain of a tub or shower nearby after you flush this means it is the air vent for the plumbing stack in this run. An air vent serves this purpose: 1) Removing sewage odors to the outside of the home and if you ever poured gas out of a can and than opened up the little air cap it allows for the liquid to pour a lot faster. Same with your plumbing the air vent allows air into the system and your drains run properly. Sometimes when you flush and it is not vented at all or properly the noise you hear is the plumbing sucking air out of a nearby drain ie. your shower or tub in that bathroom.
Granite, Quartz, any type of hard stone surface makes for an excellent countertop in your kitchen. Granite is by no means on the way out and represents the #1 countertop I have been installing in my projects in the past few years. I would only say to stay away from Silestone, I have seen it fail in many kitchens and don't recommend it to anyone. Silestone was big into the idea that the kitchen sink is formed as part of the countertop so you can just wipe things directly off the countertop into the sink. However, I have seen it almost have a shattered look like glass in the bottom of many of silestone sinks. Do some research between the benefits of different forms of stone for your countertops, but they are all excellent products and really it comes down to the look, color, and texture that you like.
You can go to an association or I always like to use my online resources. You can use a company like service magic or find a local community online, and see who they recommend and who they use. It is always better to find a general contractor that has actually done work for someone you know and can give an honest recommendation.
I think Nancy has got us all beat with the quick answer of 144 S.F.