I didn't study Italian but I know someone who did. She loved studying it, and really enjoyed her year abroad. She also visited Italy on a few holidays otherwise. So it sounded like she had a very positive experience with it!
In terms of the degree, it's worth noting that any modern languages degree (including joint honours degrees) are more than just language learning courses. Learning about the culture etc is an integral part of learning the language beyond very basic level. A joint honours degree should necessarily include both language study and cultural studies of the country/countries speaking the target language.
If your only interest in the language is for gaining competency in the language then you might find just studying the language through your university's language centre outside of your studies more suitable, or just doing a single honours course and taking just the language modules as optional modules outside your programme (which is usually possible). Note that without cultural context you may find your language skills become limited in some respects.
The rest of the questions I can't really answer although I assume in general the workload should be similar to if you were studying any other subject, although language modules tend to require a bit more ongoing effort to keep on top of the grammar/vocab (you can't just cram for the exam at the end!).