If they approved my e-file, do I have to mail forms like W-2, 1099-R, etc. or just the voucher with payment? Thanks

If your tax return was e-filed and accepted, you do not need to send to the IRS your forms W-2, 1099-R, etc... You just keep them in your tax records.

If you are paying your tax due by check, just send your check with the voucher 1040-V,