We currently have some acreage (undeveloped) and our home in Texas. We want to sell both and roll over the proceeds to one home. Will there be any taxes due on the proceeds, if all the money is rolled over?
Then we would like to sell the new home in about four years and avoid the tax on gains to $500,000. Is this possible?

Unless the acreage is adjacent and can be reverse split back into your home parcel, you will have to pay (long or short term) capital gains tax on the acreage since it is not a residence and does not qualify for the residence exclusion. Assuming you have lived in the residence for 2 out of the past 5 years, the residence qualifies for the $500,000 MFJ exclusion. There is no roll over under the new exclusion. There never has been an exclusion or roll over allowed on acreage that is not a part of the residence. You can do the new exclusion every 2 years so you don't have to wait 4 years if you don't want to do so. I suggest you read about residential sales under the FAQ and do a search on the subject to help educate yourself on this subject.