you are not well Ali - hope all those dogs are looking after you well!
I have never trimmed Maggie - she is only one and has not needed it yet. As for unruly hair on back that won't lay flat (which Maggie has a lot of) - night before show, bath and put a towelling robe on (or any other such thing) when they are dry take it off and you should have nice flat hair! Only worth doing before a show though because 5 minutes rolling in the garden and it's back to normal! Not sure what you do about the hair on the neck - I would like to know this too!
My cavy has long hair between her toes which I trim - I use blunt ended sisssors and pull the hair up from between the toes and then trim downwards away from foot - got better with practice - made quite a mess the first time but it always grows back so don't worry too much about making a mistake. We had a hot summer once and felt sorry for Tilly so brought some electric clippers and gave her a shave - she looked most odd and I sort of regreted it but it all grew back - now I just thin out her long hair and do her feet.