Do not bother looking for the holes where the ink comes out by the way - they are microscopic. An HP Engineer told me that cheaper inks really can cause problems - apparently the electrical resistance of the ink is important and the circuitry in the cartridge holder can burn out with some cheaper inks. I feel it is worth the money to have a 'proper' A1 plotter. Note that you cannot easily get true A1 wide roll feed plotter paper. Watch out for the new higher resolution plotters.
More dots means more memory and slower output.
Make sure the plotter has sufficient memory or even a built in Hard Disk drive to cope with the type of drawings you produce. Talking of resolution don't pay too much attention to quoted resolutions for plotters - a 'real' resolution of 600 x 600 in mono and 300 x 300 in colour produces very good results and is fairly quick. Note that I find it safer to leave the default paper type alone - at least for plotting. Changing the paper type can affect the printed output - not always in the way you would expect. If ' Details ' then click ' Add port '.