Time Machine needs file sharing mode

I have a Time Capsule (1rst Gen 2008, 500 Go) 56GB left, connected through Ethernet.

I just rebuilt the index but i still find odd it needs 4 mn to backup 10MB every hour

I have strange errors

mds[78]: ERROR: _MDSChannelInitForAFP: AFPSendSpotLightRPC failed -1

and

mds[78]: (Error) Volume: Could not find requested backup type:2 for volume

also,

1) i need to enable file-sharing (with airport utiliy), or Time Machine won't start

2) the name of the disk is incorrectly spelled in Time Machine preferences (with a "-1" at the end, as if there were two disks with the same name. There are not)

3) Time Machine seems to be using afp for the backup

com.apple.backupd[3242]: Attempting to mount network destination URL: afp://MyDisk

i wonder if there is a problem in the way Time Machine is configured

Any ideas ?