Can coffee filters be used in the absence of filter pads?

I would not advise it. For one, you are not going to get adequate filtration and two, I believe a coffee filter is not going to hold up through a complete filtering of 6 gallons of wine.

Can this be used to remove sediment from purchased wine that was never filtered?

It should work but if you are just doing a bottle at a time, it would be a little pricey. Refill packs run around $13 for 5 filters so you would be looking at $2.50ish for each filter you use.

Does this filter better than doubled coffee filters, which I use for my final racking?

I've only used Vinbrite filters. The kit comes with three filter types, depending on your needs.I would have to say yes, it should do a better job than double coffee filters.

Hello, I have a 1000 l of wine and would like to filter, please let me know how many pads I need for filter 1000l?

I apologize but I’m struggling converting liters and milliliters to U.S. standards. I can tell you that depending on the filter pad you use, the number I came up with was one pad for every 25, 750ml bottles. Some people run their wine multiple times through a clean filter to clarify their wine as much as possible. Clarifying red wines is the worse. So to answer your question, 1 pad for every ~25 bottles of wine. Your results may vary.