The Yudu doesn't really make screen printing any easier. It is basically a nice compact unit but I would say you would benefit more from saving your money and buying a traditional set up that you can expand from. I have a Yudu and it works great but for a screen printing business set up I would go a different route.
Here is a place that does have kits and package deals that you may find something that will work more for a a business.
Also you may want to check out the T-Shirt forum which seems to have a lot of pros from threads I have read through.
If you just want to design shirts and sub out the printing to a local screen printer then the Yudu would be great for prototyping your designs and fine tuning them before beginning print runs. Or if you were setting up an online shop you could print up a limited supply with your Yudu and if a design takes off then you can sub out the printing as well.
This film is specially designed to accept inkjet printer ink without smearing (I wouldn't get it wet, however). After putting a pattern on this film, you would then cut out the positive spaces, so that you can use it to use it to mask your silkscreen, right? At that point, all the ink would have been removed, so nothing would be left to smear.