Yea a good shockleader is a must, or you could just use some 60lb line, you'll need that to make rigs anyway
Google these rigs, theyre basic and easy to make:
1 hook flapper/2 Hook flapper
Pully rig
wishbone rig
I normally use 2/0 hooks but it depends what your after.
Big cod will need atleast a 4/0, same for big bass, for flat fish i'd say a size 1 or something.
Mussels are also a good cheap bait thats easily to collect, works well for cod.
Now the weathers warming up the main fish people want to catch is Bass but theres also others about.
Butch