Hi there, I'm a will writer ([email protected] if you want further info).
Yes, your dh can be an executor. Most married couples appoint one another as executors, but two others in default, so that on the first death, the surviving spouse acts as sole executors, then on the second death, the default execs act. There should be two default execs in case a trust arises, which would be the case if any of the beneficiaries are under 18.
Mirror Wills are virtually identical, although there can be some differences. Essentially, mirror wills are Husband appointing Wife as executor and beneficiary (then going on to say how the estate is to be distributed if she's died first), and the other Will will just be the other way round, so Wife appointing Husband etc.
I'm a high street lawyer with over 20 years experience but set up Marlow Wills earlier this year as a freelance will writing service. Because my overheads are tiny compared to a high street practice, my charges are only about half (usually around £75-80 for a single, £130-£140 for mirror wills).
Feel free to PM or email me for more info.