llc/partnerhip returns are due 3/15/2020. if it cant't be completed by that date then an extension must be file on or before that date. there is no need for individuals to file an extension if they'll have the k-1's in time to file their personal returns by 4/15/2020
yes you can manually enter any necessary data from the 2018 return.
for the partnership while there is no federal income tax, there may be a state income tax. you'll need to check on that. any tax would be due by the due date of the return. states also have different rules as to extensions. some if you file a timely federal extension you have a timely state extension. others require you to file for state extension and pay any tax due with it. TT should permit the filing of the 1065 extensions.
for payment of partnership tax, if any, go to the state website. virtually every state is set up for electronic payment.
if the individual returns need to be extended, any balance is due 4/15/2020, each partner can go to the IRS website and make an electronic payment. select extension payment when it asks. making the extension payment thru the IRS website negates the need for an individual to file an extension. print out the document to keep as proof that payment as submitted.
