Blockwork extension onto stone cottage

[Klem]

Good morning all, this is my first post, I apologise if it's a lengthy one. My current project is renovating my stone cottage on a very exposed Welsh hillside.
Planning has been granted to remove an old lean too and build a single storey extension on the side and remove a conservatory from the rear of the house and build a single storey extension in its place, and a full width dormer to the rear built up off the gable ends. The architect who produced the drawings has specified it all to built in blockwork.
At some point in its life my cottage has been coated in a horrible stipple coat cement render, and the interior is coated in cement coat and gypsum plaster up to 2 & 1/2 inches in places.
On the drawings it specifies using a wall starter kit to join the new blockwork to the old house, however underneath the render at the gable end (where the lean-to was) the stones are uneven and I'm not sure how to go about fixing the wall starter kit. I'm also concerned that the this horrible render may be what is stabilising the stonework on the corner of the house where the wall starter kit needs to go.
My first question is, how would you go about fixing the wall starter kit to this?
I have a brick layer lined up and he's said to grind channels into the stone work to create a level surface to fix wall ties to, so my second question is, is this correct and should I remove the render or strip back a small section to fully expose the stone work or is there an alternative method that can be used to fix the wall ties to create a water tight joint between old and new.
I will be doing most of the work myself so as much advice as I can get would be massively appreciated.

Photo 1 is the corner at the gable end where the wall starter kit needs to be fixed
Photo 2 is closer Photo of hodge podge construction in that part of the wall.
Photo 3 is the same corner viewed from the interior.
Photo 4 is the stonework on the rear of the property.
Photo 5 is the profile of the stonework on the rear of the property.

Many thanks in advance,

Klem.

 

[Cubist]

Sorry you've seen no replies thus far but you placed this query in one of the less well traveled forums - would have done better by now in the main 'Discussions' forum - but here's my twopenneth.

I'm not clear on precisely where you want/plan to have the exterior face of the new wall to appear but this starter systems require a continuous, flat and vertically plumb location. If you do not intend that to be the section of rendered wall then you will have to make good the old 'hodge-podge' as you call it to create the needed surface. If the render though turns out to be weak of failing you should remove and replace the loose stuff.

In terms of fixings I would suggest you use chemical wall anchors rather than any kind of expanding plug or anchor bolts - these could conceivably cause elements of the wall to cracks and fail. Chemical anchors though will allow you to drill the holes where needed before installing the anchors. In this wy you can ensure that the hole does not collapse before each anchor is installed.