But you're doing that without any knowledge of web services, IIS, InfoPath, or .NET development really? Do you have access to this database now? Do you understand its schema and how to write a web service that properly retrieves and submits data to/from that database? Do you know how to properly pass credentials? These aren't necessarily my questions to you but questions to ask yourself or whoever it is that assigned you a task of building a custom, complex solution for a client without knowledge of the products required to make it work.
You mentioned you were "downloading VS now." You don't already have and use it regularly for other development? It's not just a random tool you download. It's expensive and is very powerful but only used by people who write code for a living. Does your company just have floating licenses out there that allow anyone to get it whenever they want?
For the record, IP2003 definitely can be used to accomplish your goal and using a web service to submit/retrieve data to/from a database is definitely a best practice. IP03 is about to be 2 versions old, though, so be wary of that. You need to make sure you know the database type, too. Is it SQL, Oracle, or something else? Do you have rights to modify the data within it?