Students completing a diploma will usually undertake 25 points at level one, 37.5 points at level two and 37.5 points at level three. If one subject is 12.5 points then that means that 8 sequential language subjects are required to complete your diploma. Cross crediting just means that by doing a language as a breadth in your degree, up to four language subjects can count towards your Diploma as well. In this case they are allowing 4 language subjects that will count towards your Bachelors degree and your Diploma so you pay these upfront or by HECs as part of your Bachelors. The other 4 language subjects you have to pay in addition and they will not count towards your Bachelors but just to your Diploma only. Which means you will need to complete an additional 4 subjects that will count to your Bachelor's so you have the required credit points to graduate. So compared to a student that is not completing a diploma of languages, you are paying for an extra 4 subjects instead of 8 subjects because of the cross-crediting mechanism.
1) If there is 8 subjects in a year. A student that uses cross crediting will do 24 subjects as part of their bachelors (4 of which are counting towards their diploma) and do 4 subjects that are purely counted towards their diploma.
2) Some students don't wish to choose cross-crediting because they love uni so will do 24 subjects as part of their bachelors and 8 subjects purely as part of their diploma. So compared to 1) they are doing 32 subjects instead of 28.
Note you can cross credit as many subjects as you want up to the maximum of 4.
Unless you choose 1) pathway then your degree will be extended by an entire year no matter what. By doing the 1) pathway the only way you can condense your degree into 3 years is if you perform well in 1st year and maintain a H2B average. You will be able to contact the student centre and they will be able to grant you the ability to overload your semesters. So you can complete 5 subjects in a semester instead of the standard 4 subject load for your 2nd year and 3rd year. However, alot of students steer clear of this as overloading can be a bit overwhelming and jepordise your ability to perform in subjects and maintain the Grade Point average that is required to get into honours.
You will not be able to complete honours until you have satisfied all your credit points for your Diploma of Languages and Bachelors degree. As honours year is a full year full time study load already that is not part of your Bachelor of Commerce degree, but an addition.
The link with the pdf just offers you different ways that you can spread out your Diploma during your undergraduate degree.
Hope this helps!