Outgoing (hardware) load balancer and gateway and DHCP

Question

Here is the scenario:

Two (or more) aDSL routers --> Internet
192.168.1.1
192.168.2.1
...
    /\
    |
    |
    \/

Hardware Load Balancer      
192.168.255.1
    /\
    |
    |
    \/

  Workstations
 192.168.255.2
 192.168.255.3
 ...

First of all, is the scenario mentione above doable?

Requirements:

1) 192.168.255.3 is able to access ONLY 192.168.2.1 . Also, noone else is able to access 192.168.2.1. However, when 192.168.2.1 internet is not available,192.168.255.3 shouldn't stay offline and should be routed to 192.168.1.1 (Again, only when internet is not available on 2.1)

tl;dr: Dedicated outbound routing, with failover depending on internet availability

2) DHCP Server

3) Outgoing load balance (not interested in adsl pairing, just outgoing load balance)

Reccomendations on hardware setups? Note that I would prefer if the load balancer was a dedicated unit, and not a linux box for example.