yes there is
its awkward but you push the analogue stick right for r2, left for l2 and up for both
For games that require an R2 button (typically PS1 ports) it is usually mapped to the analogue stick. Pushing it to the right will simulate an R2 button press.
There is none.
If a game requires the R2 and L2 buttons, these are usually mapped to the PSP's analogue stick to the lower left of the screen.