unfinished download

If I don't finish downloading a batch torrent will I be able to watch the ones that are finished or will it result in not being able to watch any?

Well, I normally like to let the batch torrent finish, then watch it. You should check some of the threads out, some people have had some problems when they watch the finished episode but haven't let the entire torrent finish.

depends on client and settings.

In azureus, you can start up a batch, and check the status of individual eps in it. You can also tell it to download specific files in the batch with higher or lower priority. If the file is listed as finished in the files list in azureus (double-click on the file and click on the "files" tab), you're good to go, watch it and enjoy.

I am not an authority on bittornado, but I'm told it has a similar feature, where you can get select eps.

Note that if you're not altering download priority, it's very unlikely that your individual episode in a large batch will be done until the whole batch is done. That means you're unlikely to be able to watch it. Most clients download data in random order, and just store the data in a linear way starting from the first file in order to avoid having to pre-allocate the whole batch. Meaning, just because the file is the final size doesn't mean the data is in the right place, or is the right data for that file.