@TQ32, First explain your concern to the rep and ask them if they have done any similar houses. Then ask them for the address and go look for yourself. If they can't point to examples then find another company who can.
Ideally both houses would get the job done at the same time, so just on the off chance it would be worth discussing it with your neighbour. It might be something they are interested in and the company might be able to reduce the price a bit for both jobs.
With regards the dashing, it is important that the material used (and the process) is suitable. Some systems (rigid boards) can't be applied directly to dashing (although some systems are ok if the boards are sealed with adhesive around the edges to prevent convection behind the insulation). A Rockwool system like this might be an alternative solution. http://ecofix.ie/technical-information/
With regards the brickwork, that's straightforward enough. Brick slips can be bought to match the existing brickwork and then stuck on to mimic the original. Brick slips can also be made from salvaged brick if necessary. Again, look at examples that the company have done and while you're at it have a chat with the owners and ask them if they are satisfied with the company.