BGP deployment

Short time listener & first time caller.
I have some questions regarding, the kind of configuration that is typically done, on a BGP-enabled router sitting at the edge of the network. My questions may have already been answered earlier, if that’s the case, then someone please point me to the relevant mails…

  1. In general, how many BGP peers should an edge router be capable
    of handling, more specifically, how many E-BGP peers
    and how many I-BGP peers are typically incident on one edge router.
  2. In most situations the routes to the stub networks are manually injected into BGP.
    I feel that’s the most common scenario but was wondering if running some IGP
    between the stub network and the provider edge router and then importing the routes
    from this IGP into BGP is also common ? Is this also done frequently enough ?
    Another option could be to run a BGP session between the stub network and
    provider edge router. Is this preffered ?
    Any help/suggestions would be highly appreciated.

Regarding point 1, that heavily depends on what you are using for an edge router, more details would be good.