Yes you can. However, before doing so, you should check the posting, translation, and open period or summarization processes that created these files. The GL_POSTING_INTERIM_XX tables are temporary tables 

No.      

You can run any GL program from the command line. 

You need to use the Find Batches window to find the Batch on the Enter Journals form. From there, you can delete the batch. The first window that is displayed when you navigate to the Enter Journals form 

A batch is available for posting on the Post Journals form that has no debit or credit amounts shown for it. You post the batch and the Posting execution report contains the error 'No journal entry lines for this batch'.  Now the batch is greyed out on the Post Journals form and I can not find it on the Enter Journals form. How can I find and delete this batch?

This batch does not have any journals. You need to use the Find Batches window to find the Batch on the Enter Journals form. From there, you can delete the batch. The first window that is displayed when 

I am trying to submit a batch for posting and receive the error 'APP-8058: This form failed to submit your posting concurrent request.  Please ensure that your concurrent manager is running.'

Set the 'Printer' profile option. This profile option must be  set to successfully submit most concurrent requests. 

NO.  When you drop a summary template, and reassign the child values, Summary Account Inquiry does not save the history of the previous accounts.   

4 requests:  1 for the parent and 3 for child accounts.  

Does Add/Delete Summary Program dynamically create accounts that meet the summary template criteria?

NO, It just groups the existing accounts to meet the summary template criteria. 

Can the "Deleting" status in the Summary Templates screen be reset back to "Current" without actually deleting and reading all the summary account templates?

You cannot update the status via SQL*Plus to "Current".  These must be deleted and the summary accounts recreated.