Can I specify more than one tax
Yes. You can create a tax group.  Select one or more taxes.  Then use the tax group in the documents like sales invoice and sales order
Wed, 13 Jul, 2016 at 4:18 PM
Can I specify a tax which is dependent on another tax
Yes.   Create a tax.  Specify on which tax it depends on.
Wed, 13 Jul, 2016 at 4:25 PM