Unstopping clogged drains, toilets and sewers

I don't have enough room under my sink to get the faucet nut off.

A basin wrench is a tool designed especially for that.

What diameter trap do I need for my kitchen sink?

These are almost always 1-1/2 inches. The 1-1/4 inch traps are for bathroom lavatories.

What is the correct size of garbage disposal that I should put under my sink?

If you are replacing an existing unit that has worked well for a number of years, the old size should work fine. Otherwise, 1/3 horsepower will handle limited use once a day. A standard 1/2 horsepower will normally suffice for general use. Heavy-duty 1/2 horsepower units and larger are designed for a large volume of garbage.

My kitchen drains are clogged. What do you recommend?

While there are many methods to clear a clogged drain, the simplest ones often do the job.
* Hold off on using chemicals. Chemical drain cleaners are caustic and it's best to try other methods first. If you do use a chemical, don't use a plunger because the cleaner can splash back to burn your skin or eyes.
* Kitchen sinks often are clogged by grease. For slow running drains, try pouring a few quarts of boiling water down the drain to loosen the mass. Then run hot tap water for a few minutes to flush the pipes well.
* If flushing doesn't work, next try a plunger. Be sure the cup is flat around the drain hole to develop suction as you pump the plunger. About 10 to 12 pumps of the plunger should be sufficient.
* If plunging fails, try to auger with a wire (a coat hanger will do) or purchase an auger you-know-where.
*An inexpensive expansion nozzle, like the Drain King, which attaches to your garden hose, will allow you to use water pressure to free a clog. The nozzle, screwed onto to the hose, is inserted into the drain. It expands inside the drain so water won't flow upward.
Finally, if all those methods fail, the trap may need to be cleaned. Some have a cleanout plug at the bottom of the bend in the trap. If not, the trap must be removed. Set a pan under it to catch the water before you take it apart.
 

Do you have anything I can put in my drain line that will kill the tree roots invading the line?

There are root killers that contain copper sulfate.

What is the purpose of an aerator on a faucet?

An aerator diffuses the water to prevent splashing.

Is a trap necessary under the sink?

You need a trap to shut off odor (sewer gas) from coming into the kitchen and bath area.

Can I use plastic drain parts on metal drain parts under the sink?

Yes.

In the long run, which is better - chrome drain parts or plastic?

Plastic will usually last much longer than chrome, but you have to be careful because it can be affected by some harsh chemicals in drain cleaners.