Devang,
Prefix list offers more flexibility in editing as well as in defining the range of mask lengths
eg. you could have a single prefix list which filters a subnet x.x.x.x/21 le 24. The same would require multiple access-list statements.
Significant performance improvement in loading and route lookup of large lists
Support for incremental updates
Filtering using extended access lists does not support incremental updates.
Though with new IOS releases we can edit the access-list
The command-line interface for using access lists to filter BGP updates is difficult to understand and use, since it uses the packet filtering format.
Eg. access-list 101 permit ip host 192.168.192.0 host 255.255.248.0 which is a slight deviation from the traditional access-lists
?Greater flexibility
In regard to your second question, the following map commands are available while advertisement
route-map, suppress-map, attribute-map & advertise-map
HTH, rate if it does
Narayan