We are maintaining a database server that serve a large number of clients. Each client typically running serveral client-applications. The total number of connections to the database server (Oracle 9i) is reaching 800 connections on peak load. The windows 2003 server is starting to run out of memory. We are now planning to move to 64bit Windows in order to gain higher memory capability. As a developer I suggest moving to multi-tier architecture with conneciton pooling, which I believe is a natural solution to this problem. However, in order to support my idea, I want the information on:

1. what exactly is the typical number of connections allowed for Oracle database ?
2. What is the problem when the number connections is too high ? Too much memory comsumption ? or too many sockets opened ? or too many context switching between threads ?
3. To be a little bit specific, how could Oracle Forms application scale to thousand of users without facing this problem ? Shall Oracle RAC applied to this case ?

I'm sure the answer to this question should depend on quite a number of factors, like the exact spec of the hardware being used. I'm expecting a rough estimation or some experience from the real world.