So there's a decision tree that just about any router goes through when determining routes. The respective routing protocols (RIP, BGP, OSPF, IS-IS, static) run their own algorithms to determine the ideal path to a given prefix. If the router is presented the same route (i.e. identical network and prefix length) then the administrative distance is consulted. This is the relative priority of the various routing protocols on the box, and in most implementations the lowest value wins.
So - my understanding from Quagga is that it treats RIP routes as having a default administrative distance of 120. If you don't specify a different AD on a static route it will end up with a value of 1. As such, a static route will normally take precedent over a RIP route. In turn, if you set up a static route with an AD of 200 (for example) it will only be used if the equivalent RIP route leaves the table (this is known as a floating static route).
In your example the situation is that routes received via BGP may have one of two different AD's - one for internal BGP routes (this is 200 by default in Cisco - would assume something similar for Quagga) and another for externals (usually much lower - 20 in Cisco).
You can adjust the AD in Quagga manually. Take a look at the manual and specifically consider the
distance command under each routing protocol definition. You can see these rules in effect when you look at the routing table, where the format is usually something like x.y.z.q/nn [AA/MMMM] where AA = administrative distance and MMMM = the metric within the protocol.
As an aside - and I hope this is obvious from what I've written above - the longest prefix match is always the most important factor. A /32 received in RIP with an AD of 120 will trump an overlapping /24 from eBGP with an AD of 20. This is just basic routing, though.
Also - in almost every properly designed networking scenario there is no need to adjust AD. If this seems like the only way to approach the design I would strongly consider re-approaching the design altogether as there's lots of potential for operational issues, routing loops and the like when AD is not consistently applied.
Hope this helps.