Replication 3 servers (no replies)

Hi,
First time post...
I would like to make a setup of 3 servers that replicates as following...

server 1 holds 4 db (2 replicated DB)
- db1 populated by server 1 application
- db2 replicated from server 2 to/and data replicated reside in server 1 also
- db3 populated by server 1 application
- db4 replicated from server 2 to/and data replicated reside in server 1 also

server 2 holds 4 db (2 replicated DB)
- db2 populated by server 2 application
- db1 replicated from server 1 to/and data replicated reside in server 2 also
- db4 populated by server 2 application
- db3 replicated from server 1 to/and data replicated reside in server 2 also

server 3 holds 4 db (4 replicated DB)
- db1 replicated from server 1 to/and data replicated reside in server 3 also
- db2 replicated from server 2 to/and data replicated reside in server 3 also
- db4 replicated from server 1 to/and data replicated reside in server 3 also
- db4 replicated from server 2 to/and data replicated reside in server 3 also

server 1 is on site A and server 2 is on site B and server 3 is on site A
my plan is if a server connection fails we have access to server 1 or 2 to access all databases, server 3 is for backup export to tape only

2 questions
- is this setup possible if yes what is the best scenario / procedure to setup?
- when I backup server 3 in lock mode will it stop server 1 and 2 from collecting data and replication between server 1 and 2?