The C1000s is not your best bet for speech. It is a small diaphram condenser, what you need is a large diaphram condenser. There are about 100 different mics to choose from, and to be honest, if you close your eyes and point to a LDC in the $300-$400 price range, chances are you are going to get what you need and it will be better suited than your C1000s ( just for the record I am not a C1000 basher, I love mine and use them all the time, just not for voiceover)
Whichever mic you choose I would not record without a pop filter, unless you go with an RE20 or similar mic (which is not condenser).

I would find a preamp that that has compression and some EQ built in (aka a channel strip) unless your speaker is a seasoned pro he will probably need a little compression while being recorded to maintain proper levels.
You mentioned both "speeches" and "discourses" in your post. Does this mean in front of an audience or in a studio? If you are in a small room then some room trreatment might be in order, exposed sheetrock within 5-10 feet away from where you are recording can be a real problem. This obviously would not be an issue if you were recording in front of a group in a large room.

The list of equipment is a poor choice for this task, but if it's what you've got, you have to make it work. You don't need an additional pre-amp - the Digi002 has them built-in.

I assume that you are simply recording and that the speaker is otherwise un-amplified. Is the speaker static at a lectern or likely to be moving around?

I think I would prefer an SM57 dynamic instead of the CS1000S condenser for this job. However, the C1000S is good enough quality, and will give you perfectly acceptable intelligibility if it can be positioned a couple of feet from the speaker. You shouldn't need a pop filter at that distance.

You would do well to remove frequencies below about 120 Hz, or higher if the speaker is female. Do your compression, EQ etc in post, that is, when you are processing the recording after the event for archive or distribution.

Is your client going to be put off by a large mic stuck in their face?

I record oral histories with the elderly from time to time so I bought some lapel mics for the job.

That way there's no radical timbre changes with them going off mic, losing/changing the character of the read, and they forget its there very quickly, making the recording process a bit more transparent.

Thanks everyone - that really helped.

I'm with Boswell on preferring the SM57. If you want an even better dynamic for spoken word with less proximity effect, I'd go with an EV RE20. Very standard radio broadcast mic. Nice warm sound.

Unless you are going to have a new speaker every week with no chance to train them, I would avoid the lavalier mics. They make a lot of sense for Brent_in_Sydney's application and of course they make sense for video. But there are a lot of audio compromises. If your speaker likes to move around, there are headset mics that will be better than a lav.

If you do get a lav, get as close to choking them with it as is legal.
After melting my CPU running a fine FFT display filter I had to remove a small notch at 487Hz from the recordings.

The closer the mic is to the speaker's neck the less a problem the room is, and also helps with feedback in my situation.