Planets and panspermia in star clusters

[Auditor of Reality]

Firstly, is there a limit on how dense open clusters can get? I've heard globulars have been known to be a couple of stars per cubic ly. Could an open cluster get that dense?

Gravitational disturbances from passing stars would affect planetary formation, however what else in the cluster might affect the probability of a given star in the cluster having planets (assuming the stars are mostly sunlike population I stars)? And to what degree would the density of the cluster impact the probability of a given star in the cluster having planets? Also, might it be possible that, due to gravitational disturbances from passing stars, terrestrial planets could get pulled out of orbit and end up in another system in the cluster?

Thirdly, how much material would be exchanged between terrestrial planets in systems in a dense open cluster? If life evolved on one planet in a globular cluster (or if Earth was placed in the aformentioned dense star cluster), might bacterial or other hardy spores traveling on the material thrown up by an asteroid or comet impact be able to reach another star close by due to the smaller distances involved? Would it be possible for panspermia to operate through a star cluster, given long periods of time?

[selden]

Auditor,

Some of your questions are areas of current research.

Have you done a search through the papers published on Arxiv.org ? Some answers may be available there.

[Auditor of Reality]

Many thanks for the pointer I found some interesting papers there.

This one answered my question in rather nicely:
Lithopanspermia in Star Forming Clusters

Fascinating ...