PostgreSQL HA questions

Hello

We're looking for HA PostgreSQL solution,so have a couple of questions:

1. Is it possible for multiply PostgreSQL instances (engines,cores) to use
same DATA space? For example,to have two PostgreSQL processes which will use
same data directory,same files,and same data ? So,if You update some data in
some table over postmaster1,the process which uses connection to postmaster2
will 'see' the exact same data in the same table ?

2. Becouse of vaccuming issues,is it possible to create such a client
process which will use two identical tables,and on receiving a signal,it
will switch between those tables.For example,first a client application uses
table1,after some time,send a signal to process,it will switch using
table2,so You can freely vacuum table1 or whatsoever.After vacuuming
done,table 1 will sinchronize with table2 and keep up-to-date until You send
next signal to application,which will switch using table1,so You can vacuum
table2.

If any one has any ideas,thoughts ?

Sincerely

Dragan