I have only done these in NSW so best to check with your states act.
Commercial Buildings:
I have my own licence agreement which details the basic requirements and clearly identifies the lessees rights and responsibilies. The lessee and their legal adviser signs the licence and I always take a security deposit of at least 3 months gross rental.
Ensure that you follow up that that the electricity is placed in their name and like any lessee, that they have the correct insurances.
There is also a clause that I am allowed to show potential tenants through as required and with a minimum 24 hour notice period.
Generally, it is done over the Christmas/January when most people are not looking at leasing or alternatively I have also done it in July/August period when I contact the local accountants to fill in any vacancies that I may have in the portfolio.
Try not to use this type of tenancy for longer 6 months.
Retail Tenants (casual mall lettings)
Similar to the above with regards to paperwork and insurances but in these instances I never have them longer than 1 month at a time as the types of tenants need to rotated.
With regards to rental, it depends on the situation. If you are using it as stop gap then the quality of the tenant and the way that they will look after the property is more important than attaining top dollar.
Casual lets in shopping centres command a significantly higher rental.
Hope this helps.