Yes you will be able to use it with your Blackberry. The Anker uses USB to Micro USB for connecting to other phones. You can even use your existing blackberry cable and connect it to the USB ports on the charger.
Kathy, could you be a little bit more specific about which Asus Transformer product you have? Asus have many products with Transformer in the name. Most of the products have a unique model code e.g. TX300, T100T, TF101, TF700 etc. It would be useful if you could provide the unique model code for the product you have.
I believe it only does 5v output, but ask Anker direct as they seem to be keen with after sales queries, (they emailed asking me not to hesitate to contact them if I had any issues or questions) So I am sure they will answer pre sales enquires too.