What version of VuFind are you using? I believe that RC1's old import program should create log files under the import directory… and the newer SolrMarc indexer in the latest trunk code has much more verbose output that could be redirected to a log file for later searching.
If you're using an older version of VuFind, you might get better results by updating to a newer SolrMarc importer.
A common problem that can cause missing records is if the importer is unable to determine a unique ID for each record. Is there any chance that the MARC field you are using as your unique ID is missing for a handful of records and/or is not unique under rare circumstances?
To browse your index, have you tried going to:
From there, if you click the "Full Interface" link, you'll get a lot of options. To browse the full index, you can put in a search query of "*:*". You can adjust "fields to return" to cut down on the amount of data that comes back, and use start row/maximum rows returned to navigate through the results. Not the most convenient way of doing things, but it should be helpful.