No, nothing is omitted - like "make" and "let", you'll often see the base verb (without "to") follow "help" immediately. No pronoun is needed either - you'd only need one if you mentioned another person or group earlier. "To found" means "establish". Think of "foundation".

No I mean you can say, help do, with nothing omitted. And besides that, otherwise, you can also say, help someone do, in (my highschool textbook) grammar books, these are noted as two irrelative different terms of use of the word. I know it might sound a little silly, but that's why "help" is special-----not an auxiliary verb but it's got itself look like it is one sometimes-----help do. (have helped do, will help do, be helping do, etc are correct, too) No. Help is not like make or let. You cannot say make do or let do, even "let go" is kind of an idiom use.

It means THEY helped found the Royal Society in 1660. To 'found' something means to create, establish, commence or begin.

found here means FORM, they helped in making this society!

If something or someone helps (to) do something, they are one of several reasons for it happening. So you do not need a noun after 'help" another example could be: The drought has helped (to) make this a disastrous year for Somalia! The reason I wrote "to" in "( )" is that using " to" is optional. Hope this helps! :-)