DPC certificate

Yes not a problem

Usually when the so called certificate they should have the companies details,I should check with the previous owner there must have the Bank Details who they paid My personal experience is to get it checked out with a recognised Damp Specialist Through MyBuilder I personally do not charge for this service so there will be other Damp Specialists who will do the same

That number could be from anywhere, who installed the dampcourse,when did they install it, what were the terms of the guarantee and what was the extent of work carried out. Without this information I would be very cautious.

This rather depends on the definition of "certificate" and DPC. Most likely an injection DPC. If you know the name and contact details of the company or tradesman who installed this, and if they are still trading, then they may well be able to supply a copy. This does not actually mean what they did will work or last a particular length of time, this will depend on the wording of the "certificate". Most likley, it will mean it was done but not to any agreed standard. This is the type area occupied by old used car salesmen, so rather a mixed bag. Hope this helps.

yes if you look out side ,there should be just above damp course there you should see some round plugs ,they should be drilled in the morter joints not the actual brick work