Hi Mate
I am far from the most qualified to answer this but I'll give you what I know until someone with more knowledge/experience answers.
Firstly, there are now bench specialisation programs on the ios app. So I am guessing one of them would be the best option for you?
As for the frequency, benching more frequently will be skill development as well as normal muscle/strength gain.
With the accessories, I haven't done the bench only program but with the standard programs I run the program as prescribed and add in a bit if back/bicep work and judge it by feel. I used to prefer everything planned out so it has taken a bit of time for me to get used to it but it seems fine now.
If you are new to Sheiko I would run a cycle as prescribed and see how you feel.
I hooe that helps
James