It certainly is not a good spot to be in. However, even with the best of circumstances, you can be jailed on your 1st DWI. You definitely need a DWI Attorney to act as a go-between and take some of the heat off of you that you can't do yourself.
It may seem like a huge invasion of your privacy--and it is--but your PO can perform a warrantless search of your home. The scope and extent can be restricted by state law, but for all intents and purposes, you will just have to suffer through it. If you meet them at the door, you don't have to invite them in for dinner, but be accommodating to make the process go as smoothly as possible.
I certainly understand your frustration and concern--you are trying to help your husband after all. Unfortunately, this is one thing you cannot do for him. It is considered practicing law without a license.
Not only can you lose your CDL, but if the truck belongs to you, you can lose that to an asset seizure as well, on top of a host of other unsavory consequences. You need to contact a criminal defense attorney post haste.
Technically, no you do not need an attorney to seal your records, but that doesn't mean it's a good idea. It can be a drawn out process and the fee that you are paying likely includes filing fees to the court. The value of having an attorney handle the entire process versus you handling it on your own, only you can decide.
I applaud your desire to be proactive and seek out ways to protect yourself, but the best way that you can do that is to counsel with your attorney. They are in the best position and have the best chance of having things turn out the best for you. Part of it is human nature. Regardless, work with your attorney and let them work for you. Perhaps you will not have to worry about a trial, let alone an appeal.
Yes, you still need to have the DUI expunged. This is not something you want to attempt to do on your own. The good news is that, if as you have stated above, you meet all of the requirements, you have a reasonably good chance of success through your attorney. This is not a guarantee, and I'm sure you understand that, but your chances should be good.
I appreciate that you are being as detailed as you are, but, as an attorney, I am left with many more questions--for your sake. Please, contact an attorney that handles DWI cases. There are numerous good ones on this site. You need to realize when you are well past the point where self-help can benefit you. Based on your facts stated, that point was reached some time ago.