enough (of) other people

Look at this example:

Sam: There are enough people interested in our meeting. We can start now!
Bill: Yes, and there are enough of other people that are here just for free lunch

okay, thanks. 🙂

in the first sentence, can we add "of"?
in the second sentence, can we omit it?

many thanks 🙂

I wish Susan would appear..

Here I am... 🙂

I haven't had time to check this (and I will) but, off the top of my head, compare these sentences.

We didn't have enough people to hold the meeting - we needed 20 members for a quorum. 30 people came but only 15 of them were members.
We didn't have enough people to hold the meeting - we needed 20 members for a quorum. 30 people came but not enough of them were members.

The use of enough + noun phrase (enough people) vs enough of + noun phrase (enough of the people) is exactly the same as the use of a cardinal number + noun (15 people) vs cardinal number + of + noun phrase (15 of the people) : it specifies a subsection of something already mentioned - ie
15 of the people were members out of the 30 people present = not enough of the people were members.

And it's not just cardinal numbers, but also quantifiers like many. several etc.

He doesn't have many friends. vs Not many of his friends speak English.
There were several possibilities vs. Several of those possibilities had to be excluded

Notice how there is always a determiner - ie a word like the /his / those etc after of to show which subgroup we're talking about. I'm afraid Arbaboza's example *there are enough of other people isn't correct. It would have to be : there are enough of the other people.

enough + of also occurs in a number of fixed expressions :
I've had enough of = I'm fed up with
I've had enough of his rudeness = I'm fed up with his rudeness

to be enough of a/an + noun = to be sufficiently qualified as a...
I'm not enough of an expert to answer this question

And of course there are always times where the preposition of seems to follow enough but is really connected to another word in the sentence :I'm very fond of David vs. I'm not fond enough of David to lie for him.

Don't be confused by those - the presence of enough is irrelevant here.

So in your examples, you could say eg :

A lot of the people there didn't speak English, but there were enough other people to translate.
(You see the people as being two separate groups - those who don't speak English and those who do)
or
A lot of the people there didn't speak English, but enough of the other people did and could translate.
(You see the people as being one group, divided into two subgroups)

As always, the grammar gives us the opportunity to make meaning distinctions which are in the mind of the speaker. Grammar is choice of meaning. So I'm afraid it's impossible to say whether either or both alternatives would be possible in your case, unless you giìve the full context. It is always context and intended meaning which determines form.

Hope that helps. I will check, and will come back if there's anything to add or correct.
Sue