LSDS / LSCS integrated with custom databases, and third-party repositories ?

System

We are setting up a solution based on the Teamsite 7.2 stack, which will include Teamsite, SitePublisher, Livesite Content Services and Livesite Display Services. Most of the pages within our end-user websites (to be delivered out of Livesite) need to support a "mix" of both content components (static and dynamic content for different use cases), as well as "dynamic data" components - for data that will have to be sourced from custom databases, third-party repositories, and the like. Basically, in addition to standard "content components" on a page, we also have to support a host of dynamic data components, on the same page.

The key differentiator is that the content components will leverage Teamsite content only, and we could easily do that of course using LSDS + LSCS Runtime to fetch and render content. However, the "dynamic data components" need to query custom relational databases, third-party repositories and the like - some of which may have their own proprietary APIs as well, and some we'll need to call into using custom SQL.

Questions for this group; would appreciate the help :

1. What different methods / options are available to support this scenario ?
2. How could we leverage LSDS to do this for us - using externals ?
3. Could we also leverage LSCS to do this for us - can LSCS integrate with a external / custom data store / database / repository ?
4. Can LSCS somehow be setup as a "common service layer" that can serve both TeamSite content (via LSCS-IDOL), but also retrieve content from these custom DB's / third-party sources ?

We have done this once in the past using LSDS "externals" (wherein the external works against the custom DB and returns data in XML format to be rendered by the Livesite component), but we were wondering if with LiveSite 7.2, can LSCS itself be also used to encapsulate this "common service layer" for us, and connect to both Teamsite content (via IDOL) and external / custom databases, and hence make it transparent for LSDS components ?

Any help would be much appreciated.