T212 makes money from the CFD platform hence the entire platform is fee free. because of how CFDs work T212 can make money. trading is essentially a gamble, and most people lose that gamble, its through these actions that T212 earns its income. In return T212 makes sure to provide the best possible service.
no fees are applied to dividends that I have ever been aware of.
the difference between ISA and invest would be in the tax status. assuming that in both cases you have filled the W8-BEN form, only a 15% tax would be applied to the dividend payment.
In an ISA account that is the end of it as ISAs are tax exempt.
For a normal invest account you have to fill out lots of paperwork to submit to the government about how much you earned, the taxes paid or remaining due etc.