Given that currently the band I'm with is in final mixing for the CD, I hope I can share some experience that may help...
For the packaging... first, something GREAT that was shared by a member from his experience in design and sales: Take your alternate designs. Stand back 5-10 feet. Look at them.
Which one stands out? Which one conveys what you want to at that range? Is it a blob of color? Is it a distinct image? Does that image say what you need it to? Don't be afraid to show it to others, giving them that 'first time' view at range. That'll be how people see it in music stores, that'll be how people see it on tables at festivals, and people generally won't take a second glance at an unfamiliar product if they can't make some sort of connection with it quickly and from a distance when they first see it.
For the 'notes'... That's more of a personal decision. I guess that the basics will always be track listings, writing credits, copyright info and whatever other requirements your band personally has. Beyond that, remember that a singlefold is MUCH cheaper than multi page or multifold. If you don't need to use the interior of the fold, you can probably get away with a decent 4 color screen across one surface, folded to give both front cover and interior track listings. Anything else added would be a personal decision, and would also bear the attendant extra costs.
As to finances... I won't even attempt to suggest on that one. There are GREAT books and resources on the tax necessities of a small band, and it does vary from country to state to county to sometimes even city. Maybe even spring for a consultation with an accountant just to see if you need one. If he/she is a good accountant, they'll tell you what is needed, and how much of a benefit they can be for you. But DO make sure you do your research.
Best of luck, sir. And I'll also echo the tape idea - they don't really sell any more. I'm on the lower end of the American financial spectrum, and *I* barely use cassettes any more - the only ones I still use are compilations for driving, made from CDs at home. If you get enough interest to justify a print run, great. But I doubt you will.
Hope this is of use...
M