Yes, if there are other stars close to the neutron star, then the latter can spin quite wildly, with the jet being all over the place. It's somewhat rare, but I always prefer boosting from these than from small, narrow jets.
For example, some earlier screenshots of mine:
As for water worlds around other stars in the system: I can't tell you exact numbers, but I can tell you about Earth-likes. Currently, on the ELW list there are 506 Earth-likes in systems where the main star is a neutron star, with 246 orbiting the NS itself - so, 260 orbiting another star in an NS system. EDDN's database almost certainly has more. Now, Earth-like worlds have to satisfy much stricter criteria than water worlds do, so I'd guesstimate that there must be at least five times that many WWs in these configurations. So, sorry to say, but it's not rare.
However, if you find an Earth-like in a neutron star system, that is uncommon. So, good luck if you'll be searching for those!
