First,

The most important question to ask, "Is it melanoma?" Melanoma is a malignancy that can spread to lymph nodes and then other parts of the body.
If it's basal cell carcinoma or squamous cell carcinoma, they are growths that would continue to grow, invade, and if left untreated, could deform normal surrounding tissue but they are generally not going to metastasize. They are removed not to save one's life, but that it would keep growing if not removed.
If it's melanoma, you will want to know what stage is it. This might require more tests to give you an accurate answer.
I've had basal cell carcinoma on my lower leg and a good friend has had melanoma. She was super lucky that she mentioned it to her derm because she said it didn't look like the usual spots shown in brochures. It was discovered sooo early she didn't need any further treatment (chemo or radiation) except surgery.
My derm is one biopsy-lovin' guy. Seriously, I think he does one every other visit but my basal cell was found very early while it was still superficial.
Superficial is not just a visual diagnosis but a microscopic one made by the pathologist. It means it hasn't invaded the deeper layers of the skin. So I am grateful he is so careful. I didn't need the Mohs procedure, but just had to put what he called a "chemo cream" on the scar everyday for I can't remember how long. Several weeks IIRC.
Now I go for skin cancer screenings every 6 months. I feel like I get new freckles every week so sometimes 6 months feels like a long time.
It's good that you're going with him to his appointments. Not only so that he's not going through it alone but it's also good to have another set of ears or someone to take notes. Sometimes when you're given a lot of info at once, it's hard to remember everything later.
This might help:
http://www.cancer.org/cancer/skinca...squamous-cell-what-is-basal-and-squamous-cell
http://www.cancer.org/cancer/skinca...guide/skin-cancer-melanoma-detailed-guide-toc
Hang in there!! You're doing all the right things.

Remember, you can always get a 2nd opinion. It will either reinforce your confidence with his current doctor, or maybe shed a new light on things. Either way, it's a good idea and that's why insurance companies don't mind paying for 2nd opinions.
Good luck to your dh!!