Thanks guys for your help on Q.2. I will put that into action when I finally get my bath....er....darkroom set up.
I have had some luck on fleabay already, snagging a pair of 645 negative masks and a mounting plate for 80mm lens. I have put in a memorised request for 6x6 masks also, so eventually one might pop up.
Yesterday I had to re-visit the guy who sold me the enlarger because he had forgotten to include the 12v transformer, and this time he gave me a gadget which is labelled "Polysales Cd Se Enlarging Meter". It has an on-off switch, a turning knob labelled from 1 to 12, a hole labelled "Sensor Cell" and a light labelled "Balance". I presume that I should place it on the baseboard and turn the knob until the light comes on. Then, how the relative number relates to exposure time I don't know. I have tried to google a set of instructions, but no luck. Has anyone had experience with these meters?