Removing Rendering back to brick

Hi

Hope someone can give me advice. I have a terrace Victorian 2 up 2 down. I
bought this with rough render half way up and then stone cladding on the
first floor! Well it was cheap....

I had a small patch of damp on the front, and assumed this was the rendering
over the DPC (not so naive - I have a Certificate to say damp proofed from
company - now bankrupt) but when I chopped away a section of rendering there
is no evidence of injection holes for a DPC, and very little mortar on the
bricks either. The mortar that is there is very soft.

I am now thinking I should chop off all the rendering, and cladding and
repoint then inject a DPC. So a couple of questions I cant find help with in
the DIY books.

1 - How deep should I remove the soft mortar in my solid 9" walls. The books
say half and inch, but the mortar is very crumble and soft all the way
through the joint.

2 - Will I need up with a nice brick finish? If so how effective are the
waterproofing compounds I can paint on to offer some protection from
penetrating damp? If the bricks are a bit tatty I am thinking I can repaint
with weather proof paint anyway. I don't want render or cladding again!!!
Whaddaya think??

3 - How long do I have to leave it all before I can inject the DPC?

Any advice/stories most welcome.

Thanks