Hmmm, these kind of questions are what we get paid a lot of money to come and ascertain for clients.
Question c) I cant answer for you with any degree of accuracy.
The others kind of go hand in hand. While I havent done much work on slow connections using SQLNet, there is no really quick answer. The short answer is that Oracle applications tend to be quite network intensive and can very easily eat up whatever bandwidth you give it.
That said, careful design of the application can minimise network traffic substantially. Trying to get fetch as little data as possible down the pipe is obviously beneficial, and if the application is designed to get the database server to do as much of the work as possible and then bring back as small data sets as possible, you should see some benefits. Use stored procedures to do more remote work.
Other things to consider, try do some reading up on SQLNet configuration. I think there are some settings which try and optimize the way SQLNet applications talk to each other.
Also, do some tests to see if building an application web server (IAS) might help. Its a middle tier that can sit behind the slow connections, usually on the database server, or on a machine on the same high speed network. The benefit here (though not always) is that all Oracle Forms and Reports processing is done on the webserver, and only relevent display information is sent to your web browser, thereby minimizing network traffic on the slow connection.
The number of people who can share these type of applications across a single 64Kbit link varies, and the answer lies more on the pessimistic side, unfortunately. Nevertheless, factors like how often people are actually fetching across the link, the size of the fetches and how many people are hitting it simultaneously naturally affect the final answer. But dont get too excited, I dont think that you will get too many people on a 64K link. 5 concurrent without people getting too frustrated is very optimistic. But this number could go up to 20+ if the app is small and there is only sporadic work being done. Do lots of tests first and try and have them emulate as close as possible to your real life situation.
Sorry - this reply might seem quite long, but it is in fact very brief. It might give you some food for thought and some ideas to check up. But a write up here is not going to ultimately going get you an answer.
