Answer:
There are several ways to tell us your address has changed:

Methods to Change Your Address
Method Action
IRS form Use Form 8822, Change of Address or Form 8822-B, Change of Address or Responsible Party - Business
Tax return Use your new address when you file
Written statement
Send us a signed written statement with your:

full name
old and new addresses
Social Security number, ITIN, or EIN
Mail your signed statement to the address where you filed your last return.

Oral notification Tell us in person or by telephone. We'll need you to verify your identity and the address we have on file for you. Please have ready your:
full name
old and new addresses
Social Security number, ITIN or EIN
We may request additional information to verify your identity.
If you filed a joint return and are still residing with the same spouse, both you and your spouse should provide your names, social security numbers, new address and signatures on the form or statement.

If you filed a joint return and you now have separate addresses, each of you should notify us of your new, separate addresses.

Authorized representatives filing a form or written statement to change an address for a taxpayer must attach a copy of their power of attorney or Form 2848, Power of Attorney and Declaration of Representative. Unauthorized third parties can't change a taxpayer's address.

Changes of address through the U.S. Postal Service (USPS) may update your address of record on file with us based on what they retain in their National Change of Address (NCOA) database. However, even when you notify the USPS, not all post offices forward government checks, so you should still notify us.

For changes of address relating to an employment tax return, we issue confirmation notices (Notices 148A and 148B) for the change to both the new and former address.

It can generally take four to six weeks after receipt for a change of address request to fully process, however there may be delays.

Answer:
Yes, but an actual copy of your Form W-2 is only available if you submitted it with a paper tax return:

Transcript

You can get a wage and income transcript, containing the Federal tax information your employer reported to the Social Security Administration (SSA), by visiting our Get Your Tax Record page. Refer to Transcript Types and Ways to Order Them and About Tax Transcripts for more information.
You can also use Form 4506-T, Request for Transcript of Tax Return. Check the box for Form W-2, specify which tax year(s) you need, and mail or fax the completed form. Most requests will be processed within 10 business days from the IRS received date.

Note: The IRS may be able to provide wage and income transcript information for up to 10 years. However, current processing tax year information may not be complete until the earnings are reported. This transcript doesn't include any state or local tax information reported by your employer to SSA on Form W-2. If you need W-2 information for retirement purposes, you should contact the SSA at 800-772-1213.
Copy

If you e-filed your tax return or you didn't attach your Form W-2 to your paper return, then use one of the transcript options above. Otherwise, you'll need to contact your employer or SSA for a copy.

The quickest way to obtain a copy of your current year Form W-2 is through your employer. Your employer first submits Form W-2 to SSA; after SSA processes it, they transmit the federal tax information to the IRS.
If you can't get your Form W-2 from your employer and you previously attached it to your paper tax return, you can order a copy of the entire return from the IRS for a fee. Complete and mail Form 4506, Request for Copy of Tax Return along with the required fee. Allow 75 calendar days for us to process your request. We will waive the fee for taxpayers impacted by a federally declared disaster. (For more information, see Publication 3067, IRS Disaster Assistance, Federally Declared Disaster AreaPDF)

Answer:
You can file Form 1040-X, Amended U.S. Individual Income Tax Return electronically with tax filing software to amend your Form 1040, 1040-SR, 1040-NR, or 1040-SS/PR for the current or two prior tax periods. If amending a prior year return originally filed on paper, then the amended return must also be filed on paper. See Form 1040-X, Amended U.S. Individual Income Tax Return, frequently asked questions for more information. You still have the option to file a paper version of the Form 1040-X and should follow the instructions for preparing and filing the paper form.

Additional Information:
Filing Your Taxes
Instructions for Form 1040-X, Amended U.S. Individual Income Tax Return
Tax Topic 308 — Amended Returns
Subcategory:
Amended Returns
Category:
Electronic Filing (e-file)

Answer:
Contact an IRS customer service representative to correct any agency errors by calling 800-829-1040 (see telephone assistance for hours of operation). Unfortunately, this may result in you receiving a paper check.

Subcategory:
Refund Inquiries
Category:
IRS Procedures

Answer:
To claim your child as your dependent, your child must meet either the qualifying child test or the qualifying relative test:

To meet the qualifying child test, your child must be younger than you or your spouse if filing jointly and either younger than 19 years old or be a "student" younger than 24 years old as of the end of the calendar year.
There's no age limit if your child is "permanently and totally disabled" or meets the qualifying relative test.
In addition to meeting the qualifying child or qualifying relative test, you can claim that person as a dependent only if these three tests are met:

Dependent taxpayer test
Citizen or resident test, and
Joint return test
Additional Information:
Whom May I Claim as a Dependent?
Publication 501, Dependents, Standard Deduction and Filing Information
Subcategory:
Dependents
Category:
Filing Requirements, Status, Dependents