New user. Yes I did search the KB

New user. Couple of questions:

Here's my config:
Source PC using AB11 to send backups via FTP to an FTP server with 2 physical disks.
FTP server has 2x 900GB drives. Both are dedicated to this.
Backups are file level and generate about 250GB of backups a night even with Incremental bu's.

Here's what I want to do. (I have 2 questions.)
I want to do nightly incremental bu's to the FTP server. Then I want to move the .TIB files off the server so I don't fill it. I was going to use the AB11 post job processing ability to MOVE files from one of the drives to the other so then I can burn those files to DVD and remove them from the server.

If I remove the .TIB files from the target FTP location, will AB11 recognize it as not having done a bu and then do a full bu? If I leave the index files in place, will that prevent it from thinking it needs to do a full bu?

Right now, the bu jobs are slicing the files into 2GB pieces. Has anyone seen any problems with having it slice them into 4.5GB slices since these are going to be put on DVD? I found the setting where it says to slice automatically or specify a size, but it doesn't have a setting for NOT slicing the files. Is the 2GB setting something to do with FTP time out restrictions or Windows disk restrictions?

Thanks in advance for any info.