Electrical faults?

I have a 2000 Iveco Daily 59-12. I've owned it for 2.5 years since a conversion to a horsebox. However, it has always had the odd electrical fault, Shorts, new alternator etc. etc. Are these vehicles known for these type of faults? Latest problem is the starter motor turns even when the ignition is turned off anf when jump started the jump leads heat so we remove them and when the ignition key is turned on the speedo indicator rises to 50mph. Any ideas?