Faster yum for multiple servers

[Al Sparks]

A couple of questions on yum.

When I ran
   yum update

I would occasionally get errors like,
********
grep-2.5.1-17.4.i386.rpm  100% |=========================|  52 kB    05:03     
error: rpmts_HdrFromFdno: MD5 digest: BAD Expected(41f49a1430e2729628b3002893b9f634) !=
(46fe019379b1917ed12daf1862e5d1de)
grep-2.5.1-17.4.i386.rpm  100% |=========================| 169 kB    00:18   
********

I ended up running 
   yum update
about 3 times, before it finally downloaded all the rpm's and
proceeded to install them all.

Once I upgrade one server, is there a way to set it up so it serves
its own updates?  That way subsequent updates on other servers don't
take so long.

If not, can I copy over headers and rpm's from and to the correct
place on a new server and then run "yum update" so all it has to do is
upgrade w/o downloading?
   === Al