Invest and cfd you have to pay capital gains tax (above the annual allowance). You can have multiple ISA (of the same type - eg shares ISA) provided that they are opened in different years and you pay money into only one of them in any tax year (so even if you open one with a Ā£1 you cannot put money into another isa in that tax year).
If you hold shares (or cash) in an isa for 10 years (or any period) and then cash it in, it is exempt of UK capital gains tax