Load Balancing Drupal 7 - HELP!

Hi,

We already have a working Drupal 7 with the following setup:
Internet -> Web Server -> App/DB server

Now, we're planning to expand our infra to cater more users with this
setup:

Internet -> Web Server/Load Balancer ->
App Server <-> App Server
Primary DB

Notice that we'll now have 2 app servers that will host Drupal and a
separate primary db (we'll have a secondary "mirrored" db for backup and
for other systems that wants to get data from our system)

Now my questions are:
1. Will this affect client session handling in any way?
2. We're using memcache and boost modules, will this affect their caching
functionalities especially boost module since cached pages/files are stored on
the App server?

Any ideas on this would greatly help us on designing this architecture.

Thanks in advance.