Spouse visa renewal questions

[Hammer2001]

My wife and stepdaughter came to live with me in the UK in 2014. I am a British Citizen by birth.
I have a few specific questions I am trying to find answers to, and wonder if you can help:

1. My wife’s current passport containing her visa is in her maiden name. Her passport is not due to expire until Jan 2018 (six months after her visa is due for renewal). So will we have to renew her visa in maiden name, or could we use married name?

2. If we do have to apply in the maiden name, can we update her BRP to the married name once the passport has been renewed in the married name. What would this cost?

3. My Step-daughter who is 13, was issued ILE when they arrived in 2014. Her current passport containing the visa expires in 2018, but the ILE states an expiry date of Aug 2017. I’m confused by this as I thought ILE was the same as ILR and therefore we do not need to renew her visa.

4. If it is correct that she does not have to renew her visa: When her passport expires in 2018 can she apply for apply for a BRP to replace the visa in then what would be her old passport, so that she can prove her immigration status? If she can, am I correct in thinking she would have to apply for a BRP NTL at a cost of £308?

5. A complication to this is we would ideally all like her surname to be changed to match our married name. We are looking at deedpoll for which there would be no problem changing the name, as my wife is the only person with legal parental responsibility., but we are unsure it is recognized in her home country, and therefore she could not get a new passport issued with the new name. But would we be able to use it for a BRP even if the passport showed a different name?

6. And would this cause future problems with immigration at airports and ultimately British citizenship?

It would be easiest if we could get their passports renewed with the new names before we renewed the visa, but we have been told by the embassy in the UK for their home country, that passports can only be renewed back in the home country and that they'd have to travel back there to do so. This really isn't practical, due to my step-daughter having to miss school, and we also have a 7 month old baby. And who knows how long it would take!

We are planning to go there next year for a two week holiday, but it is very unlikely we would get the passports renewed in time before we left, not to mention the complications it would cause to the booked return flights if travelling back under different passports!

Why does it all have to be so complicated! Any advice you can offer would be greatly received!